review article how the knowledge of interactions between...

Review ArticleHow the Knowledge of Interactions between Meningococcus andthe Human Immune System Has Been Used to Prepare EffectiveNeisseria meningitidis Vaccines

R Gasparini1 D Panatto1 N L Bragazzi1 P L Lai1 A Bechini2

M Levi2 P Durando1 and D Amicizia1

1Department of Health Sciences University of Genoa Via Pastore 1 16132 Genoa Italy2Department of Health Sciences University of Florence Viale GB Morgagni 48 50134 Florence Italy

Correspondence should be addressed to R Gasparini gaspariniunigeit

Received 21 January 2015 Accepted 9 June 2015

Academic Editor Nejat K Egilmez

Copyright copy 2015 R Gasparini et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

In the last decades tremendous advancement in dissecting themechanisms of pathogenicity ofNeisseriameningitidis at amolecularlevel has been achieved exploiting converging approaches of different disciplines ranging from pathology to microbiologyimmunology and omics sciences (such as genomics and proteomics) Here we review the molecular biology of the infectiousagent and in particular its interactions with the immune system focusing on both the innate and the adaptive responsesMeningococci exploit different mechanisms and complex machineries in order to subvert the immune system and to avoid beingkilled Capsular polysaccharide and lipooligosaccharide glycan composition in particular play a major role in circumventingimmune responseTheunderstanding of thesemechanisms has opened newhorizons in the field of vaccinologyNowadays differentlicensed meningococcal vaccines are available and used conjugate meningococcal C vaccines tetravalent conjugate vaccines anaffordable conjugate vaccine against the N menigitidis serogroup A and universal vaccines based on multiple antigens each onewith a different and peculiar function against meningococcal group B strains

1 Introduction

The immune system protects humans from attack bymicroorganisms such as bacteria viruses protozoa fungiparasites and organisms such as helminths The skin isthe first barrier and its protective action is enhanced bybodily secretions such as sweat and sebum which exert abroad antimicrobial activity [1 2] The mucous membranesare protected by external and internal secretions such astears saliva and mucus which contain molecules that canneutralize bacteria Tissues such as the skin and mucousmembranes are populated by immune cells which can actagainst the microorganisms that circumvent the first physicaland biochemical barriers

The immune system is very complex and its defensiveresponse is subdivided into innate and adaptive responses[3] The innate response triggers an immediate nonspecificgeneral action and is activated by typical signs of infection

The adaptive response is able to develop a highly specificextremely accurate action which is stored in the so-calledimmune memory

This paper provides an overview of the interactionbetween the immune system and Gram-negative bacteriawith particular reference to Neisseria meningitidis in theperspective of developing new vaccines against this pathogen

2 Gram-Negative Bacteria and Immunity

21 Outer Membrane Components Over thousands of yearsbacteria have developed several mechanisms whereby theycan circumvent the immune system Specifically Gram-negative bacteria possess a complex of envelopes whichallow the selective passage of nutrients into the cell and theexcretion of metabolic waste outside Structurally Gram-negative bacteria possess an outer membrane (OM) which

Hindawi Publishing CorporationJournal of Immunology ResearchVolume 2015 Article ID 189153 26 pageshttpdxdoiorg1011552015189153

2 Journal of Immunology Research

together with the peptidoglycan and inner membrane (IM)delimits the periplasm and cytoplasm compartments Manymolecules of glycolipids especially lipopolysaccharide (LPS)emerge from the outer leaflet of theOMwhile from the innerlayer of the OM lipoproteins reach the peptidoglycan withwhich they engage Moreover proteins such as porins crossthe OM these are very important for the active passive andselective permeability of small molecules ions and water [4]Most porins have a trimeric structure and an oval shape Thebacterial porins perform many functions indeed they helpthemicroorganism to adhere to the cells of the host tissue andto evade the defencemechanisms of the human body therebyfavouring invasion of the hostThey are also able to elicit bothinnate and adaptive immunity Porins can inhibit phagocyticactivity [5] and activate the complement system by meansof both classic and alternative pathways [6] For instanceNeisserial porins can activate the transport of NF-120581B intothe nucleus of B and dendritic cells (DCs) [7] The DNANF-120581B complex then recalls other proteins such as coactivatorsandRNApolymerase which transcribe theDNA intomRNAfinally this mRNA is exported to the cytosol and translatedinto proteinsThis leads to a change in the function of the cellfor example the cell may begin to produce proinflammatorycytokines

Porins are clearly involved in the induction of proin-flammatory activity although it is not known which toll-like receptors recognize them By contrast it is known thatLPS stimulates toll-like receptors 2 and 4 [8] Three distinctregions characterize LPS namely lipid A which fixes themolecule to the outer leaflet of the OM the core polysac-charide which binds to lipid A by means of a disaccharidephosphate bridge and antigen O which is the most distalportionThe general structure of LPS is fully conserved whilethe core oligosaccharide is highly variable

Toll-like receptors are a family of conserved signal trans-ducers able to induce an innate immune response To date atleast 11 mammalian TLRs have been identified Their stimu-lation by bacterial components activates the innate immuneresponse TLR2 recognizes peptidoglycan lipopeptides andbacterial proteins However it is interesting that LPS canoverstimulate the innate immune response thereby elicitinginflammation As a result the normal defences may notfunction correctly Furthermore it should be borne in mindthat TLR5 recognizes flagellin which is the main componentof bacterial flagella [9] For example mutations of the TLR4gene contribute to development of severe meningococcalinfections [10] In addition through the recognition of NmeningitidisDNA TLR9 exerts strong protection against themicroorganism [11]

22 Innate and Adaptive Immune Responses The innateimmune system is able to detect other conserved microbialcomponents called pathogen-associated molecular patterns(PAMPs) such as nucleic acid structures lipoteichoic acidand peptidoglycan [12] The pattern recognition receptors(PRRs) of immune cells include in addition to TLRs theNOD-like receptors (NLRs) and the RIG-1-like receptors(RLRs) which are able to recognize microbial componentsin the cytosol [13] TLRs NLRs and RLRs are able to activate

mitogen-activated protein kinase (MAPK) and the transcrip-tion of NF-120581B factor A different set of NLRs helps to activatecaspase-1 and the consequent assembly of inflammasomes[14]

The granulocytes and macrophages are the first cellsthat participate in the activation of the innate immuneresponse Shortly afterwards the DCs and natural killercells are activated Specifically neutrophils produce antimi-crobial proteins such as LL37 alpha and beta defensinsenzymes [15] interferons (IFN) alpha beta and gamma C-reactive protein and chemokines contribute to activating thecomplement cascade Macrophages produce reactive oxygenspecies (ROS) (eg H

2O2) and reactive nitrogen species

(RNS) Subsequently DCs which can also be activated byTLR2 and TLR4 activate natural killer (NKs) cells [16] andinduce maturation of CD4+ T cells [17ndash22]

Many bacterial components are able to stimulate theadaptive human immune response Porins can activate thetranslation of NF-120581B in the nucleus of B and DCs while classI Pilin E induces highly specific antibodies (Abs) and classII induces cross-reacting Abs Furthermore complementcascade activation as well as particularly C3b activationopsonizes antigens thereby enabling APCs to activate theadaptive response

3 Neisseria meningitidis and Immunity

31 Meningococcal Genome Meningococci have developedseveral ldquoimmunoescaperdquo strategies [23] the molecular basesof which can be understood by taking into account the natureof the Neisserial genome Progress in the field of molecularbiology and the introduction of high-throughput technolo-gies (HTTs) have tremendously advanced our understandingof the complexity of the Neisserial machinery By usingsophisticated approaches such as whole-genome sequencing(WGS) and microarrays functional genomics investigationshave uncovered the mechanisms that facilitate or hinder Nmeningitidis growth colonization and invasion and havehelped to explain its extraordinary intrastrain variation andadaptation to the environment Other techniques such asgenome-wide association studies (GWAS) have shed lighton the pathogen-host interaction and the hostrsquos susceptibilityto the microbe Genomics and postgenomics have not onlyincreased our knowledge of the biology and pathogenesisof N meningitidis but proved to be extremely useful indiscovering candidate antigens and in developing effectivenew vaccines [24]

Being a naturally competent pathogen N meningitidishas a highly dynamic plastic and flexible genome with a sizerange of only more than 2000 kilobases [25] This genomediffers from other microbial genomes in that it lacks some ofthe typical two-component systems and sigma factors [26]Despite being relatively small and compact it has elaborateda variety of mechanisms that contribute to explaining its highadaptability both to host and to environment Meningococ-cus is usually polyploid containing up to 2ndash5 genomesmdashpolyploidy being a sign of virulencemdashwhile N lactamicais monoploid [27] Neisserial pathogenicity is intrinsicallypolygenic [28] and is given by a variety of different pathogenic

Journal of Immunology Research 3

islands (PAIs or genomic islands GEIs) including gonococ-cal genetic islands (GGIs) [29] and a recently discoveredmeningococcal disease-associated (MDA) island [30]

The nature of the Neisserial chromosome and the pres-ence of extrachromosomal material contribute to explainingan important immunoescape strategy known as structuralor antigenic variation which consists of camouflage ofthe Neisserial repertoire expressed Basically it can involvehorizontal or lateral gene transfer (HGTLGT) (mainly viatransformation and to a lesser extent via conjugation andphage transduction) and allelic exchangerearrangement ofgenes or gene portions taken up from the environment(Table 1) In addition as its genome contains multiple copiesof certain genes for example opacity factor proteins andpilins [31] homologous intragenic recombination also resultsin frequent surface structural variation

Moreover the pathogen hosts a number of prophagesfrom the Mu-related family to the phage l-related groupand the family of filamentous M13-like phages [27 32] Themost widely studied sites for phage integration are known asduplicated repeat sequence 3 (dRS3) [26] which belong tothe family of Neisserial intergenic mosaic elements (NIMEs)Plasmids such as pJS-A andpJS-B also play an important role[33]

Another surface modulation occurs via phase variationa process involving the modulation of gene expression via amechanism of onoff switching (transition from an expressedstate of the gene to an unexpressed one or vice versa) Besidesthis kind of ldquofunctionalrdquo phase variation Neisseria can alsoundergo a ldquostructuralrdquo switch namely a transition betweentwo forms of a gene product The genes which are involvedin this strategy are termed ldquocontingency genesrdquo [26] and canbe coupled and interlinked in structures called phasevarions(phase-variable regulons) [34] which have a regulatoryfunction Phase variation includes a variety of sophisticatedmechanisms [35] such as slipped strand mispairing (SSM)[36] microsatellite instability [37] and reversible insertionof minimal mobile elements (MMEs) [38] Therefore thesemechanisms can involve single nucleotides (homopolymericrepeats) or complex nucleotidic structures (short tandemrepeats) occurring either upstream of a gene in the promoteror within an open reading frame (ORF)coding sequence(CDS) Changes upstream of a gene result in modulationof its transcriptional efficiency and therefore of its finalprotein concentration This is for example the case of Opcporin A (porA) and fetA genes Alterations within a genewhich insert de novo stop codons alter the full translationof the gene An example of this mechanism is provided bythe opa genes and the genes coding for adhesins such asnadA [39] Phase variation of opa genes has been extensivelycharacterized they occur in four distinct copies and code forsimilar but not identical proteins Phase variation can thusinvolve one copy or another independently of each other andcan result in eleven variants In this case phase variation istherefore equivalent to antigenic variation Besides opacityfactor proteins phase variation can involve up to hundredsof genes [40] from the genes coding for pilins [41] or forproteins involved in genome maintenance and DNA repair[42 43] to genes encoding proteins involved in the cell cycle

control and regulation [44] autotransporters [45 46] orenzymes like the pilin phosphorylcholine transferase pptA[47] or the glycosylasemutY [48] among others [49 50] thereader is referred to Table 2 which provides a more detailedoverview of the phase-variable genes Moreover new mecha-nisms leading to phase variations have been discovered [51]

The mechanism implying MMEs involves different kindsof genetic elements such as the Correia repeats (CRs) andthe Correia repeat-enclosed elements (CREEs) known alsoas the Neisseria miniature insertion sequences (NEMIS) [5253] which constitute about 2 of the Neisserial genome[54] Other genetic elements are the insertion sequence (IS)elements such as IS1016-like IS1106 IS1301 [55 56] andIS1655 [57]

It is worth noting that the number of genes involvedin phase variation is enormously greater than for any otherpathogen studies so far [58] Some genes are ldquophasotypesrdquothat is to say they play a role in carriage and are downregu-lated favouring host persistence [59]

As already mentioned in some cases antigenicstructuralvariation and phase variation albeit conceptually two distinctmechanisms cooperate in increasing the genetic complexityof the Neisserial genome Antigenic variation of LPS forexample can derive from phase variation of one or moreenzymes involved in the synthesis of the oligosaccharidechain by SSM or by modification of LPS for example byglycosylation [60ndash62] sialylation [63 64] or acetylation[65 66] which moreover confer resistance to neutrophil-mediated killing

Thus both antigenic and phase variations concur inenabling Neisseria to evade the immune system [26 27]

32 Meningococcal Capsule LPS and themeningococcal cap-sule (CP) are the two major virulence factors of N menin-gitidis Specifically the capsule displays a large variability ofsurface antigens on the basis of which 13 different N menin-gitidis serogroups have been identifiedThe CP contributes inan important way to the camouflage of the microorganismwhich thus can better circumvent the immune systemrsquosdefencesThe clearest expression of this phenomenon is givenby themolecular mimicry [67]This can be seen in the natureof the polysaccharide CP of serogroup B meningococcus ahomopolymer of 1205722-8-linked sialic acid which is identicalto a neural cell adhesion molecule NCAM-1 [68] Moreoverlacto-N-neotetraose (L-NNT) in the lipopolysaccharide ofvirulent strains is similar to an antigen expressed on red bloodcells [69ndash73] Further mechanisms of molecular mimicryhave been recently discovered and described [74]

During the first phase of infection meningococcus hasto avoid the surface defences of the nasopharynx such asthe peptides secreted at the mucosal surface [90] and IgAsecretory Abs [90 196] To this end the meningococcus canaggregate into clusters and produce abundant OM vesicles(OMVs) thus managing to hide its surface antigens and todeflect the action of the surface defences from the bacte-rial cell [196] In addition the CP protects Neisseria from


Table 1 An overview of the most important immunoescape strategies exploited by Neisseria meningitidis

Immunoescapemechanism Details References

Structuralantigenicvariation

It consists in the modified expression of domains which are antigenically different within a clonalpopulation by which the pathogen is able to escape the host immunity selection and circumventthe immune surveillanceIt usually involves LOSLPS opacity and pilin proteinsLOSLPS and opacity factor structuralantigenic variation depends essentially on phase variationPili antigenic variations depend on RecA-mediated recombination

[31 75 76]

Autolysis It is mediated by OMPLA [77]Blebbing andmicrovesicles formation The blebs originate as evaginations of the outer layer [78]

Capsule switchingDue to microevolution there is shift from serogroup B to serogroup C from serogroup C toW-135 from serogroup Y to W-135 and from serogroup Y to B nanostructured materials such asMWNTs and mesoporous silica increase transformational capacity

[30 79ndash87]

Capsule modification

For example modification of lipid A of meningococcal LOSLPS with phosphoethanolamineprotects Neisseria from neutrophils-mediated killingAnother example is given by the O-acetylation of capsular antigens (LpxL2 gene mutants areindeed more virulent)LpxL1 gene mutants activate TLR4 less efficiently

[88]

Genome plasticity HGTLGT (via conjugation transduction and transformation) and homologous intragenicrecombination

[25 27 3089]

Host modification Neisseria exploits a bacterial sialyltransferase scavenging available host CMP-NANA formodifying LOSLPS [70]

Molecular mimicryCP of serogroup B strain is a homopolymer of 1205722-8-linked sialic acid and is similar to NCAM-1L-NNT in the lipopolysaccharide of virulent strains is similar to an antigen on red blood cellsDMP19 acts as a DNA-mimic protein

[67 69 71ndash74 90 91]

Metabolic pathways Examples are iron lactate glutamate uptake utilization and avoidance of neutrophil oxidationburst ROS and RNS [92 93]

Molecular decoyFprB has an antigenic subdomain for binding antibodies which is not essential for thefunctioning of the autotransporter it also blebs with OMPs and LPSLOS distract the immunesystem directing the response away from the microbe

[94]

Immunotype switch LPS immunotype switches from L3 to L8L1 by lgtA lgtC phase variationLOS immunotype can contribute to immunoescape [95 96]

Phages and prophages The pathogen hosts a number of prophages from the Mu-related family to the phage l-relatedgroup and the family of filamentous M13-like phages

[25 30 89]

Phase variation

High-frequency reversible changes can occur in the length of SSRs (of capsule LOS opacityfactor porin adhesin invasin autotransporter haemoglobin receptor DNA mismatch repair andpilin genes termed as contingency genes and organized in modules called phasevarions)Other repeat sequences can be REP2 CRs CREEs and NIMEsTransposon-like elements can play a rolePhase variation mediates resistance to antibioticsPhase variation mediates carriage persistence

[50 52 59]

Pilin conversion andmodification

Pilin is posttranslationally modified by addition of a glycan two phosphorylcholines and aglyceramido acetamido trideoxyhexose residue [97 98]

Plasmid Examples of plasmids that can contribute to Neisseria variability are pJS-A pJS-B [33]Recruitment of humancomponents of immunesystem

Neisseria escapes complement-mediated killing recruiting and sequestering fH to its surface [91]

Temperature-regulateddefence

RNA thermosensors finely tune the expression of CP components LOS and fHBP thusprotecting against human immune killing [99]

CMP-NANA cytidine 51015840-monophospho-N-acetylneuraminic acid CP capsule CRs Correia repeats CREE Correia repeat-enclosed element DNAdeoxyribonucleic acid fH complement factor H fHBP fH binding protein HGT horizontal gene transfer lgt prolipoprotein diacylglyceryl transferase L-NNT lacto-N-neotetraose LOS lipooligosaccharide LPS lipopolysaccharide LGT lateral gene transfer MWNTs multiwalled nanotubes NCAM-1 neuralcell adhesion molecule 1 NIME Neisserial intergenic mosaic element OMPs outer membrane proteins OMPLA outer membrane phospholipase A RecArecombinase A REP2 repetitive extragenic palindromic sequence RNA ribonucleic acid RNS reactive nitrogen species ROS reactive oxygen species SSRssimple sequence repeats TLR toll-like receptor


Table 2 An overview of the most important genes and gene products of Neisseria meningitidis involved in immunoescape mechanisms

N meningitidismolecule Immunological role Reference

aniA A nitrite reductase it protects Neisseria from nitrosative stressduring both colonization and invasion

[90 100ndash102]

App It is phase-variable [103]ausIMspA An autotransporter and a serine protease it is phase-variable [45 46]Biofilm (and molecules involved in the biofilmsynthesis such as autA or hrpA or optimizingpathogen survival in biofilm such as the alpha-peptideof IgA1 protease adhC estD)

Biofilm protects from macrophages adhC is involved inS-nitrosoglutathione metabolism and in glutathione-dependentdetoxification system EstD is involved also in Neisseriacolonization

[104ndash108]

Blebs (with OMPs and LPSLOS) and SOMVs They protect from neutrophils-mediated killing and NETs theydivert the immune response away from the pathogen [78]

Capsule and molecules involved in the capsulesynthesis such as kpsC kpsS

It activates TLR2 pathway it increases serum resistance and itinhibits the classical pathway of complement [109ndash111]

Cas9 and the CRISPR-Cas systemCRISPR-Cas9-mediated repression of bacterial lipoproteinexpression facilitates evasion of TLR2 by the pathogen it isinvolved in gene expression and regulation

[112 113]

cbpA It mediates zinc piracy and protects from nutritional immunity [93]

Cps As a gene it is involved in the capsule biosynthesis as RNA it actsas a thermosensor Cps gene amplification protects the pathogen [99 114]

CrgA It is involved in the regulation of pili and capsule expression itplays a major role in the infectious cycle of Neisseria [114ndash116]

Css As a gene it is involved in the capsule biosynthesis as RNA it actsas a thermosensor [99]

ctrA ctrDAs genes they are involved in the capsule export as RNAs they actas thermosensors IS1301 in the IGR between sia and ctr operonsmediates resistance to Abs

[99 117 118]

cycP It is involved in denitrification metabolism and protects Neisseriafrom nitrosative stress [90 119 120]

dam It is involved in phase variation and modulation [42]dcaC It is phase-variable [40]

dinB A DNA polymerase IV belonging to the SOS regulon it is involvedin phase variation and modulation [42]

DNA mismatch repair genes (fpgmutLmutSmutYrecA recN uvrD) They are phase-variables they protect against oxidative stress [42 48 51

121]drg It is involved in phase variation and modulation [42]

farA farB farR They remove antimicrobial peptides proteases lysozyme andacids from the bacterial cytosol and protect the pathogen [122 123]

fbpA fbpB They are involved in phase variation and modulation [51]Feta It is involved in phase variation and modulation [124ndash126]

fHbp (formerly known as GNA1870) It is involved in phase variation and modulation it protectsNeisseria from complement-mediated killing binding fH [90 127]

frpA frpB frpC They are phase-variable they can act as a molecular decoy [124 125128]

funZ It is a site of bacteriophage insertion it is phase-variable [49]

fur It is involved in phase variation and modulation it tunes the geneexpression of virulence genes [102 129]

ggt It regulates pathogen growth [130]

Ght It is involved in the capsule biosynthesis and in the resistancemechanisms of the pathogen [131 132]

gltT It favours meningococcal internalization into human endothelialand epithelial cells it regulates pathogen growth [133 134]

H8 AAEAP motifs are target for generation of blocking Abs [135ndash138]


Table 2 Continued

N meningitidismolecule Immunological role ReferenceHaemoglobin-linked iron receptors (hpuA hpuBhmbR) They are involved in phase variation and modulation [43 139ndash141]

Hfq A RNA chaperone it is involved in stress response and virulenceand is a pleiotropic regulator of protein expression [142]

hsdS It is phase-variable [49]

IgA proteaseIt cleaves secretory IgA hinders Ab binding and function and mayplay role in biofilm formation it cleaves lysosomal LAMP1 inepithelial cells moreover it is phase-variable

[122 142143]

katA It confers resistance to RNS including peroxynitrite (PN) protectsagainst ROS and detoxifies H2O2

[90 102 122144]

Laz A lipid-modified azurin it protects against hydrogen peroxide andcopper toxicity it promotes Neisseria growth and survival

[135 138145]

lbpA lbpBThey are involved in iron acquisition and metabolism they arephase-variable moreover the release of LbpB enables Neisseria toescape from complement-mediated killing

[90 122146]

lctP Its inactivation results in C3-mediated cell lysis [102 147148]

lgtA lgtB lgtC lgtD lgtE lgtGThey are involved in LOS biosynthesis and are phase-variable forexample lgtA or lgtC phase variation mediates LPS immunotypeswitch from L3 to L8L1

[60]

LOSLPS It protects from macrophages strains of the same species producedifferent LOS glycoforms [122]

lptA It adds a phosphoethanolamine group to lipid A and confersresistance to defensins and cathelicidins [90 149]

Lst LOS sialylation (by the enzyme Lst) prevents complementdeposition and phagocytosis by neutrophils

[122 150]

mesJ It is phase-variable [49]Msf It binds to vitronectin it increases serum resistance [151]

Mip It tunes gene expression [102 152153]

misRmisS They are phase-variable they are involved in capsule regulationand modification [114 154]

mltA (formerly known as GNA33) It tunes gene expression [155]mntAmntBmntC They protect against oxidative stress [122 156]modAmodB They are phase-variable [34]

msrAmsrB They are involved in the methionine sulfoxide reduction and theyrepair oxidized proteins [122 157]

mtrCmtrDmtrE They protect against cationic antimicrobial peptides and toxichydrophobic molecules

[122 158159]

nadA and its regulator nadR

It binds to Hsp90 recruits ARF6 and Rab11 and activates humanmonocytes and macrophages triggering IFN-gamma and R-848dependent pathways it interacts with beta1 integrins it isphase-variable

[39 160ndash165]

nalP

An autotransporter protease it cleaves C3 facilitates degradationof C3b and enhances Neisserial survival in human serum itstabilizes the biofilm moreover it is involved in the processing ofother proteases such as the proteases which release LbpB whoserelease enables Neisseria to escape from complement-mediatedkilling NalP processes also App and IgA1 protease it has animportant role in the virulence of the pathogen

[24 102166]

Nhba (formerly known as GNA2132) It tunes gene expression [167]

nhhA

It activates TLR4-dependent and independent pathways it triggersapoptosis in macrophages it increases serum resistance andprotects from phagocytosis and complement attack it is essentialfor colonization

[168 169]


Table 2 Continued

N meningitidismolecule Immunological role Referencenif S It is phase-variable [49]

nirK It protects Neisseria from nitrosative stress during colonization andinvasion [170 171]

norB

It favours the pathogen growth enabling utilization andconsumption of NO during microaerobic respiration enhancespathogen survival protects Neisseria from nitrosative stress duringcolonization and invasion decreases and downregulates theproduction of NO-regulated cytokines such as TNF-alpha IL-12IL-10 CCL5 (RANTES) and CXCL8 (IL-8) and prevents host cellS-nitrosothiol formation

[100 119120 170 172]

nspA It binds to factor H and inhibits AP [122 173ndash175]

nsrR It is involved in denitrification metabolism and protects Neisseriaagainst nitrosative stress [176 177]

oatW oatY They tune gene expression [178]

Opa

It interacts with CEACAM promoting endothelial cell attachmentand upregulating endoglin (CD105) and cooperation with 1205731integrins it elicits innate host defences and actively suppressesadaptive immune responses that would eliminate the pathogen

[179ndash184]

OpcIt binds to vitronectin it inhibits AP and it increases serumresistance it elicits innate host defences and actively suppressesadaptive immune responses that would eliminate the pathogen

[179ndash182 184]

oxyR It regulates catalase expression and is involved in the protectionfrom oxidative stress [185 186]

P36 It is involved in Neisserial adhesion [187]

pacA pacB They are involved in the composition and regulation ofpeptidoglycan membrane [188]

pglA pglB pglG pglH They are phase-variable [60ndash62]

Pili

They alter the expression levels of human genes known to regulateapoptosis cell proliferation inflammatory response adhesion andgenes for signaling pathway proteins such as TGF-betaSmadWntbeta-catenin and NotchJagged

[189]

pilC1 It interacts with mucosal surface and mediates the crossing of theBBB [41 169]

PilE pilS They are involved in nonreciprocal recombination-based antigenicvariation [76]

PilE pilV They bind to CD147 for vascular colonization they mediate alsoNeisseria internalization [190 191]

pilP pilQ They are involved in pilus biogenesis and outer membranestabilization [51 192]

porAIt binds to fH C3b C4b and C4bp (more strongly underhypotonic conditions) it increases serum resistance it is involvedin phase variation

[122 139173]

porB

It inhibits factor H-dependent AP it interacts with TLR1 and TLR2and activates I120581B MAPKMAPKK and PTK pathways leading toCD86 upregulation to IL-6 IL-12 and TNF secretion in B cellsand DCs and to IgB secretion in B cells

[122 173]

pptA It is phase-variable [47]

PpxIt is an exopolyphosphatase whose mutation protects Neisseriafrom complement-mediated killing it interacts with the AP of thecomplement activation

[64]

rmpM It is involved in phase variation and modulation [193 194]


Table 2 Continued

N meningitidismolecule Immunological role ReferenceSialic acid synthase (neuB siaA siaB siaC synC) They are phase-variable [102]

sodB sodC They protect from phagocytosis by humanmonocytesmacrophages [102]

tbpA tbpB (also known as tbp1 tbp2) They are involved in nutritional immunity [121]

TdfF It is involved in intracellular iron acquisition and is found only ingenomes of pathogen strains [28]

Temperature sensors (such as RNA thermosensorslocated in the 51015840 UTRs of genes necessary for capsulebiosynthesis the expression of fHbp and sialylation ofLOSLPS)

Activated by coinfecting pathogens they recruit mechanisms ofresistance and immunity escape [99]

tonB It is involved in nutritional immunity supplying energy to thepathogen [93]

Uncharacterized proteins (NGO1686 NMB0741NMB1436 NMB1437 NMB1438 and NMB1828)

They protect from nonoxidative factors but their mechanisms arestill not understood NMB1436 NMB1437 and NMB1438 areputatively involved in iron metabolism

[122 195]

Uncharacterized factor (NMA1233) It is involved in phase variation and modulation [26 51]xseB It is involved in phase variation [26]znuD It protects from neutrophils and nutritional immunity [92]Ab antibody AP Alternative Pathway ARF6 ADP-ribosylation factor 6 App adhesion and penetration protein BBB blood-brain barrier cbp calprotectinbinding protein CEACAMs carcinoembryonic antigen-related cell adhesionmolecules CRISPR clustered regularly interspaced short palindromic repeats ctrcapsule transport apparatus damDNAadeninemethyltransferase drg dam replacing gene fur ferric uptake regulator ggt gamma-glutamyl aminopeptidasehsp heat-shock protein IgA immunoglobulin A lbp lactoferrin binding protein lct lactate permease LOS lipooligosaccharide Mip macrophage infectivitypotentiator mltA membrane-bound lytic transglycosylase A IGR intergenic region Msf meningococcal surface fibril Msr methionine sulfoxide reductaseNadA Neisseria adhesion A NhhA Neisseria hia homologue A oat O-acetyltransferase OMV outer membrane vesicle opa opacity-associated protein aopc opacity-associated protein c pac peptidoglycan O-acyltransferase pil pilin por porin RNA ribonucleic acid RNS reactive nitrogen species Sodsuperoxide dismutase SOMVs spontaneously released OMVs Tbp transferrin-binding protein TLR toll-like receptor UTRs untranslated regions uvrultraviolet resistant

cationic antimicrobial peptides (CAMPs) including catheli-cidin [196] Conversely the presence of capsular polysaccha-ride restrains the invasion and colonization of the nasopha-ryngeal barrier by hiding the adhesins and invasins of themeningococcus [143 158] On the other hand the presence ofthe capsule may allow the microorganism to pass unharmedthrough the intracellular environment by exploiting the sys-tem of cell microtubules at least in the case of serogroup BNmeningitidis [197]Moreover the CP is essential formeningo-coccal growth and survival in the bloodstream and cere-brospinal fluid increasing serum resistance During the dif-ferent stages of infection the capsule may hinder or promotethe survival of N meningitidis in the human host indeedthe microorganism can modulate the production of capsulecomponents which depends on 4 genes three of whichmdashsiaA siaB and siaCmdashare situated in the cps locus The siaDgene induces the production of polysialyltransferase whichallows the polymerization of sialic acid For instance inthe early stages of infection the production and assemblyof sialic acid are downregulated [198] Another example ofpolysialyltransferase system is given by oatWY [178]

In addition to the above-mentioned actions the mostimportant virulence activity of the CP is probably the signif-icant impairment of both Neisserial adherence to DCs andthe phagocytic killing of bacteria indeed the CP inhibitsboth the opsonic and the nonopsonic phagocytosis of Nmeningitidis [199] It prevents the formations of effective Absagainst N meningitidis

CP downregulates both classical and alternative com-plement pathways and prevents the proper insertion ofthe membrane attack complex (MAC) [200 201] LPS alsocontributes to inhibiting MAC deposition [201 202]

Moreover CP switching contributes to escaping detectionand killingThis is a complex phenomenon due to microevo-lution and usually involves Neisserial strains expressing sialicacid (eg the shift from serogroup B to C from serogroup Cto W-135 from serogroup Y to W-135 and from serogroupY to B) [79ndash82 203] The molecular basis is provided by theallelic replacement of the sialic acid CP polymerase

Surprisingly nanostructured materials such as multi-walled carbon nanotubes (MWNTs) and mesoporous silicahave been found to increase Neisseriarsquos transformationalcapacity [83 84]

33 Major and Minor Adhesion Mechanisms of N menin-gitidis N meningitidis possesses a multifaceted system ofadhesins such as pili and other systems of adhesion (ieopacity-associated proteins OpA and OpC) Adhesion isprobably a coordinated process mediated first by pili whichare composed of several proteins themost important of theseis Pilin E (PilE) [204] but Pilin C (PilC) [205] and the secretinPilinQ (PilQ) [206] have also been described PilE is themainconstituent of the Neisseria type IV pilus In 1984 Diaz etal identified proteins I and II as the main components ofthe type IV pili and noted that Abs against protein I werehighly specific [207] Subsequently Pilin E was classified as


belonging to class I and class II Class I Pilin E is highlyvariable while class II Pilin E is highly conserved [208 209]For this reason class II Pilin E has been suggested as a can-didate antigen for a vaccine against meningococci [147] Theregulation of pilin genes is quite complex [97 115 116 190]

Other components are as follows pilV [210] pilP pilD(a prepilin-processing leader peptidase) pilF and pilT (trafficNTPases) pilG (involved in the pilus assembly) pilM (pilusbiogenesis protein) and pilW (involved in the pilus stabiliza-tion) [148] among others

Although the interactions between type IV pili and cel-lular receptors are not completely known they may interactwith a membrane cofactor protein named CD46 receptorand with alpha 1 and alpha 2 integrins [211] However it isknown that pili contribute to the aggregation of Neisserialcells [212] This fact associated with the ability of pili to actas a signalling protein by interacting directly with the 1205732-adrenergic receptor contributes to the depletion of junctionproteins thus helping meningococcus to pass through theepithelial and endothelial cells and subsequently to cross theblood-brain barrier (BBB) [75 213]

Although pili are essential to the first phase of Neisserialadhesion to the cells of the airways other adhesionmoleculessuch as LPS and porin A intervene to strengthen themicrobial bond In particular OpcA and OpcC appear tobe very important indeed OpcA binds carcinoembryonicantigen cell adhesion molecules (CEACAMs) heparan sul-phate proteoglycan (HSPG) and integrins [179ndash183 214] Opcproteins can combine with HSPGs and through vitronectinand fibronectin with their integrin targets FurthermoreOpa proteins are able to elicit innate human defences thatfavour the survival of N meningitidis while actively sup-pressing adaptive immune responses that would eliminate thepathogen [184] The variability of the expression of differentOpa proteins could play a major role in prolonging the stateof infection by circumventing the humoral host immuneresponse [215]

The adhesion and penetration protein (app) [103] whichis a member of the autotransported family of secretedproteins owes its name to its ability to adhere to humancells thereby favouring the entry of Neisseriae To circum-vent the immune system meningococci possess formidablemachineries that allow them to secrete proteins in dif-ferent manners in particular Neisseriae mainly use theautotransporter pathway (also known as type V secretionsystem) [216] The first-described protein belonging to theautotransporter superfamily was an IgA protease from Ngonorrhoeae [217] MspA (meningococcal serine protease A)is another putative autotransporter protein Not all strainsof Neisseria gonorrhoeaemeningitidis possess the gene forMspAAusI (also known as NMB1998) However Turner etal [218] demonstrated that convalescent sera from subjectsaffected by serogroupB invasive disease recognized theMspAantigen NhhA (Neisseria hiahsf homologue A also knownas Hsf) and Neisserial adhesin A (NadA) also belong tothe autotransporters Nhha contributes to bacterial adhe-sion by binding heparin sulphate and laminin In additionthrough the activation of caspase NhhA increases the rate ofmacrophage apoptosis [168 219] NadA which is expressed

by 50 of virulent strains [160] but only by 5 of the strainsisolated from carriers is of particular interest because it isone of the components of the 4CMenB (Bexsero) vaccine andbinds beta1 integrins [220]

34 N meningitidis Avoidance Mechanisms against ReactiveOxygen Species (ROS) Reactive Nitrogen Species (RNS) andAntimicrobial Peptides (AMPs) When in contact with themucosa of the nasopharynx N meningitidis can implementseveral strategies of adhesion but it must overcome manybarriers of innate immunityWe have alreadymentioned howthe capsule allows bacteria to mitigate the activity of DCsHowever it must elude other substances such as the reactiveoxygen species and reactive nitrogen species produced bymacrophages and the antimicrobial peptides produced byactivated neutrophils As already mentioned the capsuleprotectsNmeningitidis from LL-37 cathelicidin but LPS alsocontributes to the resistance of the bacterium against thiscathelicidin [156]

Furthermore the toxic action of ROS is neutralized bythe secretion of enzymatic proteins such as catalase andsuperoxide dismutase [144 149 221] The gene that codes forcatalase is katA and is regulated byOxyR [185 186 222] whileSodB and SodC code for superoxide dismutase [223] Laza lipid-modified azurin protects the pathogen against H

2O2

and cupper toxicity [135ndash138 145 176]In addition N meningitidis possesses genes which

encode enzymes able to exert a denitrification action suchas aniA CycP nirK nsrR and norB They favour the growthof the pathogen enabling utilization and consumption of NOduring microaerobic respiration enhance pathogen survivaland protect Neisseria from nitrosative stress during colo-nization and invasion by preventing host cell S-nitrosothiolformation Moreover they reduce and downregulate theproduction of NO-dependent cytokines such as TNF-alphaIL-12 IL-10 CCL5 (RANTES) and CXCL8 (IL-8) [100 101119 120 130 157 170 172 177 224]

Contemporarily already at the level of the mucosa themicroorganism must resist the complement system

Another interesting mechanism is the strategy wherebyN meningitidis escapes the attempts of the host to sequesternutrients essential for growth and survival of the pathogenThis process has been termed ldquonutritional immunityrdquo [131139] The microbe is endowed with OM receptors (such asHmbR HpuA orHpuB TbpA or TbpB and TdfF) for acquir-ing iron and other importantmetals [93 124 125 128 129 140195 225] ZnuD is a high-affinity zinc uptake receptor whichplays an important role in enabling the pathogen to evadeneutrophil-mediated killing [226 227] CbpA a receptorfor calprotectin a protein released by neutrophils duringinflammatory processes is upregulated whenN meningitidissuffers from zinc limitation [226 227] Further examplesof metabolic enzymes involved in nutritional immunity areglutamate transporters ormolecules taking part in the carboncycle [132ndash134 228ndash230]

35 HowMeningococcus Circumvents the Complement SystemThree pathways can activate the complement functionsnamely the classic pathway the alternative pathway and


the lectin pathway All three of these pathways contribute tothe transformation of C3 to C3b [231]

The alternative pathway acts by comparing self- with non-self-antigens and is activated by anything that differs from themarkers of host cells Specifically factor H recognizes host-associated molecular patterns (HAMPs) Properdin firstidentified in 1959 is another protein that can directly activatethe alternative pathway of the complement system [232] Ithas been demonstrated that properdin deficiency favoursrecurrent episodes of N meningitidis infection [233]

Meningococci produce three different variants (1 2 and3) of a protein that binds factor HThis protein named fHbp(factor H binding protein) or GNA1870 blocks activation ofthe alternative pathway of the complement system Indeedby surrounding themselves with fHbp N meningitidis cellscapture and inactivate factor H Thus it is easy for themicroorganism to survive and reproduce especially in thebloodstream and cerebrospinal fluid Hence it is importantthat the 4CMenB (Bexsero) vaccine contains variant 1 of thisprotein which is often expressed by virulent meningococcalstrains [228] Another vaccine (Trumenba) recently licensedin the USA contains recombinant variants 1 and 2 of fHbpfrom N meningitidis serogroup B A and B subfamilies (A05and B01 resp) [234 235] The proteins are produced byexploiting an advanced genetic engineering technique usingE coli as a vector

36 The Adaptive Immune Response against Neisseria menin-gitidis Microorganisms such as N meningitidis are able tochangemany exposed surface proteins while the polysaccha-rides which constitute the capsule are T-independent (TI-2)antigens and can activate B cells directly without the inter-vention of theMHCHowever TI-2 antigens donot induce anefficient secondary response and do not induce the produc-tion of avid immunoglobulins Rather they induce the pro-duction of short-lived Abs belonging to the IgM class [236]

In addition it is important to consider that in infants andchildren the development of the immune system is a dynamicprocess which begins in utero and continues for months andeven years after birth This explains why many componentsof the immune system are inefficient or partially efficient ininfancy and early childhood [237ndash239] For this reason mostcases of meningitis and sepsis from N meningitidis occurunder the age of 4 years and particularly in the first year of life

The critical role of bactericidal Abs against the exposedsurface antigens of N meningitidis has been demonstratedby several studies Indeed Goldschneider et al [240] showedthat only individuals without bactericidal Abs contracted theclinical disease In addition the successful therapeutic use ofimmune sera which markedly reduced lethality when firstimplemented by Flexner [241] has shown the central role ofthese Abs in protecting against invasive disease The opsonicactivity of Abs is also very important in the protectionagainst and the recovery from meningococcal disease as isdemonstrated by the role of neutrophils macrophages andDCs in combating N meningitidis It is also well known thatthe cerebrospinal fluid of patients contains large numbersof neutrophils full of microorganisms These clusteringsof neutrophils are known as neutrophil extracellular traps

(NETs) and massively release cathepsin G N meningitidiscircumvents these traps by blebbing spontaneously releasedOMVs (SOMVs) Other strategies that the pathogen exploitsaremodification of lipidA of LPSwith phosphoethanolamineprotected and upregulation of ZnuD [92]

The adaptive immune response has been studied in car-riers and during both the invasive period leading to clinicalmeningitis and the convalescence period T cell response isldquotwo-facedrdquo while proinflammatory T cellsmay indeed bluntthe invasive power of the pathogen the induction of theTreg response which is able to limit virulence carries theprice of the reduced effectiveness of the protective responseespecially in children [242] During infection increasedmeningococcal antibody titres can be detected from the 4thday peaking at the end of the third week or the beginning ofthe fourth week and showing a correlation with the severityof the disease and the age of the patient In the acute period ofthe disease the number of T cells generally drops while thatof B cells increases by the end of the second week IgG levelsdecline and IgM levels rise [243] In particular abnormalitiesin T cell response can be detected such as an elevatedpercentage of CD25+ and HLA-DR+ T cells an increase inCD4+ CD45R+ (suppressor-inducer) cells with subsequentexpression of activation antigens and a decrease in CD4+CDw29+ (helper-inducer) cells [244] During convalescencean age-associatedTh response can be observed specifically aTh1 response (low IL-10IFN-120574 ratio) and a highly prolifera-tive Th2 response (higher IL-10IFN-120574 ratio) can be detectedin younger and older patients respectively [245] Generallya significant CD4+ T central memory response with serumbactericidal antibodies a marker of protective immunity canbe found [246] However the above-mentioned age-relatedmucosal T effectormemory cell responsemay also be presentwithout bactericidal antibodies [247]

37 Other Immunoescape Strategies Temperature fluctuationplays an important although underscored role in microbialpathogenesis colonization invasion and host evasion Incontrast to mammals that maintain constant body temper-ature pathogensrsquo and other animalsrsquo temperature oscillateson a daily basis Loh and collaborators [99] have identifiedthe molecular bases of this temperature-dependent strategyThey have studied three RNA thermosensors located in the51015840 untranslated regions (UTRs) of genes involved in theCP biosynthesis the expression of fHbp and sialylation ofLOSLPS Increased temperature (eg during inflammationby coinfecting pathogens such as influenza virus) ldquoalarmsrdquothe meningococcus and triggers its defence mechanismsagainst human immune killing This could be a key deter-minant for the transformation of a symbiont pathogen into avirulent one However the precise nature of this mechanismremains elusive

Clustered regularly interspaced short palindromicrepeats- (CRISPR-) Cas9 is another molecular tool thatNeisseria can use in order to divert immune surveillance It isan intrinsically ambivalent device since on one hand beinginvolved in gene expression and regulation it restricts thepossibility of editing the Neisseria genome via HGTLGT orthe insertion of exogenous nucleic material and therefore it


limits the microbial variability On the other hand CRISPR-Cas9-mediated repression of bacterial lipoprotein expressionfacilitates evasion of TLR2 by the pathogen [112]

Another mechanism is the molecular decoy with whichthe microbe deceives the human immune system For exam-ple fprB has an antigenic subdomain for binding antibodieswhich is not essential for the functioning the autotransporter[94]

The example of fprB is useful to show how Neisseria canuse concurrently the previously described immunoescapestrategies fprB is subject to a high degree of antigenic varia-tion is a phase-variable gene is involved in nutritional immu-nity and moreover exploits a molecular decoy Neisserialcarbohydrates mimicking host carbohydrates circumventimmune system and at the same time exploit their mimicryto recruit fH [91]

4 Meningococcal Vaccines

41 Polysaccharide Vaccines As at least six meningococci arepathogenic in humans the development of meningococcalvaccines has been a challenge The first step towards solvingthe problem was to find a common denominator amongantigens that showed high variability In 1969 Gotschlich etal [248] correctly put the first imperfect piece of the puzzle inplace by demonstrating the possibility to extract the capsulepolysaccharide However although high molecular weightgroups A and C meningococcal polysaccharides provedimmunogenic in adults [249ndash251] important limitationsof this vaccine emerged in subsequent years Indeed whileboth group A and group C vaccines proved effective inUSA and Italian recruits [252 253] after one administrationthey displayed only short-term efficacy in older childrenand adults Moreover vaccines against serogroup C didnot prevent disease in infants and the efficacy of group Avaccines in children under 1 year of age was unclear Theimmune response occurred 10 days after vaccination Inschoolchildren and adults one dose of these vaccines seemedto provide protection for at least 3 years [254]These findingsare explained by the characteristics of the antigens containedin the vaccines Indeed polysaccharides with repeatingepitopes induce an immune response with the followingcharacteristics [255 256]

(i) The response occurs between the ages of 3 and 18months but is variable in children less than 2 yearsof age the response is usually poorthe affinity maturation of the Abs does not occur

(ii) The immunologic memory is not stimulated(iii) Almost all (gt90) Abs produced belong to the IgM

class and are produced in the spleen [257 258] Fur-thermore several studies have suggested that vacci-nation with large amounts of polysaccharides inducesimmune tolerance towards these antigens [259]

42 Polysaccharide Conjugate Vaccines Three immunogeniccarrier proteins are generally used inpolysaccharide conju-gate vaccines namely diphtheria or tetanus toxoid CRM197

(a nontoxic variant of diphtheria toxin obtained bymolecularbiology) and a complex of outer membrane protein (OMP)mixture from N meningitidis The toxoids were selectedas carriers firstly because of their immunological potencyand secondly because if the recipient had previously beenimmunized with the toxoid a booster effect was predictableMoreover under particular conditions suppressive effectscan also occur The conjugate vaccine against N meningitidisserogroup C had great success in several countries (UKNetherlands Spain Italy etc) [260] Today tetravalent con-jugate vaccines ACWY are also available in both the USA andEurope [260ndash262]

43 Vaccines against N meningitidis Serogroup B The mostdifficult problem was to prepare a vaccine against N menin-gitidis serogroup B strains Indeed the maximum expressionof camouflage is found in the capsule of these strainsSpecifically the polysaccharide of serogroup B meningo-coccal strains is a homopolymer of sialic acid residuesand has structural similarities to brain glycoproteins Forthis reason it was impossible to prepare a polysaccharideantimeningococcus B vaccine To overcome this obstacleOMVs-vaccines were developed and used during epidemicscaused byNmeningitidis serogroupB strainsHowever giventhe high variability of the proteins such as porins presentin OMVs these vaccines were effective only against veryspecific epidemic hypervirulent strains [263 264] In order todevelop a vaccine against meningococcus B other strategieswere therefore implemented

The most promising results were obtained throughreverse vaccinologyThis involves identifying the antigens forthe vaccine not in the classic waymdashthat is from the com-ponents of the bacteriummdashbut instead from the genes thatexpress the proteins with the best characteristics to be goodantigens for the vaccine To obtain a universal vaccine againstserogroup B meningococcal strains complex bioinformaticssoftwarewas also applied Following the complete sequencingof the meningococcus B genome [265] researchers at Novar-tis Vaccines and Diagnostics identified 600 ORFs whichexpressed proteins that are exposed on the surface of thebacterial cell Subsequently 350 proteins were successfullyexpressed in E coli purified and used to immunize miceLater 28 novel protein antigens able to elicit Abs withbactericidal activity were identified Finally three of these28 proteins were selected namely NHBA (GNA2132 fusedwithGNA1030 protein) fHbp (fusedwithGNA2091 protein)and nadA NHBA (Neisseria heparin binding antigen) whichis present in virtually all strains binds heparin which mayincrease the serum resistance of bacteria fHbp (factor Hbinding protein) binds factor H which enables the bacteriumto survive in theblood [266 267] thereby blocking the alter-native pathway of the complement system nadA (Neisserialadhesin A) promotes adherence to and invasion of humanepithelial cells [161 162] In addition the vaccine developedby Novartis Vaccines and Diagnostics contains a fourthcomponent namely the vesicle of the OM from the New


Zealand strains which contain porin 14 Theoretically thisvaccine should elicit bactericidal Abs against the following

(i) NHBA thus increasing the bactericidal activity of theserum

(ii) fHbp thus exposingN meningitidis to the alternativepathway of the complement system

(iii) NadA thus hindering the adherence of N meningi-tidis to epithelial cells

(iv) Porin A 14 and other components of the mixtureof proteins contained in OMVs indeed OMVs canenhance the immune response by functioning as aconjugate complex of proteins or rather a complexof adjuvants

Several clinical trials have demonstrated the immunogenicityand safety of this vaccine also named 4CMenB in infantschildren adolescents and adults [268 269] Consequentlythe vaccine has been approved by the EMA and namedBexsero [270] It has also been approved by several nationaldrug agencies (such as FDA) including the Agenzia Italianadel Farmaco (AIFA Italian National Agency for Drugs) [271]

Owing to the wide variability of Neisserial antigens aparticular laboratory test (MATS) has been developed toestimate the potential effectiveness of the vaccine Studiesconducted worldwide have shown the potential effectivenessof Bexsero which has been estimated at 87 in Italy [85]

Trumenba was approved for individuals aged 10 to 25years in the USA in October 2014 [85] The potential of thevaccine antigen was tested in the laboratory [272] and on amurine model [273 274] The immunogenicity safety andtolerability of this vaccine were investigated in a randomizedcontrolled trial in infants aged 18ndash36 months who weresubdivided into three cohorts (receiving 20- 60- and 200-120583g rLP2086 dose resp) and matched with two controlgroups one vaccinated against hepatitis A virus (HAV)and the other with a saline placebo After the vaccinationcycle seroconversions against Neisserial strains expressingLP2086 variants homologous to the vaccine antigens werefound in 611ndash889 of toddlers and against strains expressingheterologous LP2086 variants in 111ndash444Adverse reactionrates were negligible and the vaccine proved to be safe andwell tolerated [275] However another randomized phase 12clinical study found high fever rates in toddlers receiving one20- or 60-120583g rLP2086 dose (64 and 90 resp) [276]

In a randomized study performed in the USA and Europein a sample of adolescents (11ndash18 years of age) Trumenbaproved to be highly immunogenic The proportion of vacci-nees with human serum bactericidal activity (h-SBA) titreswith a ge4-fold rise against hypervirulent Neisserial strainswith different variants of fHbp was in the range of 75ndash100In another randomized clinical study carried out inAustraliathe safety and immunogenicity of the vaccine were assessedin 60 healthy adults (18ndash40 years of age) who received 120 120583gdoses at 0 1 and 6 months The percentage of seroprotectedvaccinees was 943 against the homologous strains and 70ndash947 against the heterologous strains The vaccine was welltolerated [277 278]

As fHbp is also expressed by Neisserial serogroupsother than B the anti-fHbp Abs elicited by rLP2086 mightexert a bactericidal effect on meningococci such as thoseagainst N meningitidis serogroup C as proved by Harrisand collaborators [279] and by Konar and colleagues [280]Moreover there is some evidence that Trumenba could atleast in part have an effect on carriage and reduce the riskof acquiring some hypervirulent strains [281]

44 NewVaccines The currently availableNeisseria vaccinesdescribed in the previous paragraphs are reported andsummarized in Table 3

The elucidation of immunoescape strategies andgenomics have enabled scholars to discover new potentialvaccine candidates like NMB0928 [282] or NMB1468 [283]FrpBfetA [125] LbpA and LbpB [284] adhesin complexprotein (ACP) [285] NspA [286 287] MIP [152] ZnuD[93] PilE [76] and PilQ [288] IgA protease [289] T cellstimulating protein A (tspA) [289] or the CP polymerase ofNeisseria serogroup X [290] among others [291]

Reverse vaccinology has proved to be a promisingapproach enabling researchers to develop the effective vac-cine Bexsero New highly integrated approaches whichcombine genomics with postgenomics are leading to next-generation vaccines A combination of reverse and forwardvaccinology techniques such as immunoproteome investi-gation via combined cell surface immunoprecipitation andmass spectrometry (MS) [153] and new bioinformaticsstrategies such as the protectome approach [292] are promis-ing in identifying highly conservedmotifs in known bacterialprotective antigens and using them for the design of effectiveuniversal vaccines [293 294]

5 Conclusions

Thedevelopment of effective vaccines against meningococcaldisease has been a long andhard struggle Early efforts yieldedonly partial results with the creation of polysaccharidevaccines [295] Subsequent research however led to theproduction of the conjugate vaccines [296] Today we havethe conjugate meningococcal C vaccines [297] an afford-able conjugate vaccine against N meningitidis serogroup A(MenAfriVac) [298 299] the tetravalent conjugate vaccines[270] and finally two ldquouniversalrdquo vaccines against meningo-coccal group B strains [300 301] The critical rate of coveragerequired in order to eliminate the disease is probably notamong the highest [302] Indeed the conjugate vaccine forserogroup C has resulted in dramatic reductions of cases ofthe disease [303] and created herd immunity that seems tohave had a significant effect on the carrier status of adoles-cents and young adultsThus the prospect of dominating thisvery serious disease lies decidedly in the medium term

However it must be borne in mind that we are immersedin a constellation of Neisseriae whose only survival nicheis man Although Neisseriae such as N lactamica N siccaN elongata N cinerea and N flavescens are usually ableto establish silent infection in normal humans it is notinconceivable that given the microorganismrsquos great capacity


Table 3 An overview of the currently available Neisseriameningitidis vaccines

Vaccine Manufacturer Serogroups Licensed age group Administrationschedule Components details

AC Vax GlaxoSmithKlineUK A C 2 y+ Single dose 50120583g each of meningococcal

polysaccharides

ACWY Vax GlaxoSmithKlineUK

ACYW-135

2 y+ can be givenalso at 2mo+ even

though lessprotective againstC Y and W-135

Single dose 50120583g each of meningococcalpolysaccharides

Bexsero(4CMenB)

Novartis Vaccinesand Diagnostics B 2mondash17 y

Complex dose scheduledepending on age 3doses + booster for2ndash5mo 2 doses +

booster at 6ndash23mo 2doses at 2+ y

50 120583g of each recombinant NHBANadA fHbp fusion proteinsOMVs from strain NZ98254

containing the PorA P14 (25 120583g)adsorbed on 05mgAl3+

HexaMen andHexaMix

National Institutefor Public Health

and theEnvironmentBilthovenNetherlands

B mdash2 3 and 4mo abooster dose at

12ndash18mo

OMV from two recombinantengineered strains each of whichexpressed three different PorAsubtypes (P15-2 10 P112-1 13P17-2 4 P119 15-1 P17 16 and

P15-1 2-2)

Menactra(MenACWY-DT) Sanofi Pasteur ACYW-

135 9mondash55 y Single dose

4120583g each of meningococcalpolysaccharides conjugated to48120583g of a diphtheria toxoid

protein carrier

MenAfriVac(MenA-TT)

Serum Institute ofIndia A 1ndash29 y Single dose

10120583g of meningococcal group Apolysaccharides conjugated to 10

to 33 120583g tetanus toxoid

MenBvac


Norway andNovartis

B mdash 3 doses (interval5ndash12w)

OMVs from the strain 4476adsorbed on Al3+

MencevaxA GlaxoSmithKlineand RIT Belgium A 2 y+ Single dose

50 120583g of meningococcal group ApolysaccharidesNo conjugation

MencevaxAC GlaxoSmithKline A C 2 y+ Single dose50120583g each of meningococcal

group polysaccharidesNo conjugation

MencevaxACY GlaxoSmithKline A C Y 2 y+ Single dose50120583g each of meningococcal


MencevaxACYW GlaxoSmithKline ACYW-135 2 y+ Single dose

50120583g each of meningococcalgroup polysaccharides

No conjugationMengivac A + C(MenPS) Sanofi Pasteur A C mdash mdash 50 120583g of meningococcal group C

polysaccharides

MenHibrix(HibMenCY-TT) GlaxoSmithKline C Y 6wndash18mo 2 4 6 and 12 to 15mo

Meningococcal groups C and Ypolysaccharides conjugated to

tetanus toxoid

Meningitec(MenC-CRM)

Wyeth VaccinesCanada UK and

AustraliaC 2mo+ 3 doses at 2ndash12mo 1

dose at 12mo+

10120583g of meningococcal group Cpolysaccharides conjugated to

15120583g CRM197

Meninvact Sanofi Pasteur C 2mo+ 2 doses at 2ndash12mo 1dose at 12mo+

Meningococcal group Cpolysaccharides conjugated to

CRM197


Table 3 Continued


Menitorix(Hib-MenC-TT) GlaxoSmithKline C 6wndash12mo Booster at 1-2 y


tetanus toxoid

Menjugate(MenC-CRM)

Novartis Vaccinesand Diagnostics C 2mo+ 3 doses at 2ndash12mo 1

dose at 12mo+

10120583g of meningococcal group Cpolysaccharides conjugated to 125

to 25 120583g CRM197

Menomune Sanofi Pasteur A C 2 y+ Single dose50120583g each of meningococcal


Menomune Sanofi Pasteur ACYW-135 2 y+ Single dose


No conjugation

Menovac Finlay Institute ACYW-135 2ndash55 y Single dose Meningococcal group

polysaccharides

Menveo(MenACWY-CRM197)

Novartis Vaccinesand Diagnostics

ACYW-135 2ndash55 y Single dose

10120583g of meningococcal group Apolysaccharides and 5 120583g of

meningococcal groups C Y andW-135 polysaccharides conjugated

to CRM197

MeNZB

Institute forPublic HealthNew Zealand

Chiron Novartis

B mdash mdash OMVs from strain P17b 4

NeisVac-C(MenC-TT) Baxter BioScience C 2mondash65 y

2 doses at 2ndash12mo(with an interval of atleast 2mo) 1 dose at

12mo+


tetanus toxoid

Nimenrix GlaxoSmithKline ACYW-135 1 y+ Single dose

5 120583g each of meningococcal grouppolysaccharides conjugated to

44120583g tetanus toxoid

NmVac4JN-International

MedicalCorporation

ACYW-135 2ndash55 y Single dose 50120583g each of meningococcal

group polysaccharides

Trumenba Pfizer B 10ndash25 y 3 doses (0ndash2ndash6mo) 120 120583g of recombinant fHbpadsorbed on 025mg Al3+

Zamevax ImunoloskiZavod Croatia A C mdash mdash No conjugation

CRM197 cross-reacting material 197 fHbp factor H binding protein mo month NadANeisseria adhesion A NHBA Neisseria heparin binding antigen alsonamed GNA2132 OMV outer membrane vesicle PorA porin A w week y year Al3+ Aluminum

for genetic variation nonpathogenicNeisseriamight becomehazardous to humans [304]

The challenge is still open

Abbreviations

Abs AntibodiesACP Adhesin complex proteinAIFA Agenzia Italiana del Farmaco (Italian

National Agency for Drugs)AMPs Antimicrobial peptidesAP Alternative Pathwayapp Adhesion and penetration proteinARF6 ADP-ribosylation factor 6

BBB Blood-brain barrierC3 Human complement 3 componentC3b Human complement 3b componentC4 Human complement 4C4bp Human complement 4b binding proteinCAMPs Cationic antimicrobial peptidescas CRISPR-associatedcbp Calprotectin binding proteinCCL Chemokine (C-C motif) ligandCD Cluster of Differentiation (CD4 CD25

CD45R CD86 CD105 CD147 CDw29)CDS Coding sequenceCP CapsuleCEACAMs Carcinoembryonic antigen related cell

adhesion molecules


CMP-NANA Cytidine monophosphoacetyl N-Acetyl-neuraminic acid

CRs Correia repeatsCREEs Correia repeat-enclosed elementsCRISPR Clustered regularly interspaced short

palindromic repeatsCRM197 Cross-reacting material 197CRP C-reactive proteinCXCL Chemokine (C-X-C motif) ligandDCs Dendritic cellsdam DNA adenine methyltransferaseDNA Deoxyribonucleic aciddrg Dam replacing genedRS3 Duplicated repeat sequence 3E coli Escherichia coliEMA European Medicines AgencyFDA Food and Drug AdministrationfH Factor HfHbp Factor H binding proteinfur Ferric uptake regulatorGEI Genomic islandGGI Gonococcal genetic islandggt Gamma-glutamyl aminopeptidaseGNA Genome-derived neisserial antigen

(GNA33 GNA1030 GNA1870 GNA2091GNA2132)

GWAS Genome-wide association studiesHAMPs Host-associated molecular patternsHAV Hepatitis A virusHGT Horizontal Gene TransferHLA Human leukocyte antigenshpu Haemoglobin-haptoglobin utilizationh-SBA Human serum bactericidal activityHSP Heat-Shock ProteinHSPG Heparan sulphate proteoglycanHTTs High-throughput technologiesIFN InterferonIgA Immunoglobulin AIgG Immunoglobulin GIgM Immunoglobulin MIGR Intergenic regionI120581B Inhibitors of NF-120581BIL Interleukin (IL6 IL8 IL10 IL12)IM Inner membraneIS Insertion sequence (IS1016 IS1106-like

IS1301 IS1655)katA Catalase ALAMP1 Lysosomal-associated membrane protein 1lbp Lactoferrin-binding proteinlct Lactate permeaseLGT Lateral Gene Transferlgt Prolipoprotein diacylglyceryl transferase

(lgtA lgtB lgtC lgtD lgtE lgtG)L-NNT Lacto-N-neotetraoseLOS LipooligosaccharidesLPS LipopolysaccharidesMAC Membrane attack complexMAPK Mitogen-activated protein kinaseMAPKK Mitogen-activated protein kinase Kinase

MATS Meningococcal Antigen Typing SystemMDA Meningococcal disease-associated islandMHC Major histocompatibility complexMIP Macrophage infectivity potentiatorMMEs Minimal mobile elementsmltA Membrane-boundlytic transglycosylase Amo MonthmRNA messenger RNAmsf Meningococcal surface fibrilmsr Methionine sulfoxide reductaseMS Mass spectrometrymspA Meningococcal serine protease Amtr Multiple transferable resistanceMWNTs Multiwalled carbon nanotubesN Neisseria (N lactamica N sicca N elon-

gata N cinerea and N flavescens)nadA Neisserial adhesin ANCAM-1 Neural cell adhesion molecule 1NEMIS Neisseriaminiature insertion sequencesNETs Neutrophil extracellular trapsNF-120581B Nuclear factor kappa-light-chain-enhancer

of activated B cellsN gonorrheae Neisseria gonorrheaeNHBA Neisserial heparin binding antigennhhA Neisseria hiahsf homologueNIMEs Neisserial intergenic mosaic elementsNKs Natural killer cellsNLRs NOD-like receptorsN meningitidis Neisseria meningitidisNO Nitric oxideNOD Nucleotide-binding Oligomerization

DomainNTPase Nucleoside triphosphatasesoat O-acetyltransferaseOM Outer membraneOMPs Outer membrane proteinsOMVs Outer membrane vesiclesOMPLA Outermembrane phospholipase AOpa Opacity-associated protein aOpc Opacity-associated protein cORF Open reading framepac Peptidoglycan O-acyltransferasePAI Pathogenic islandPAMPs Pathogen-associated molecular patternspil Pilin (pilC OMcell surface pilin pilD

prepilin-processing leader peptidase pilFtraffic NTPase pilG pilus assembly pro-tein pilM biogenesis protein pilP pilotprotein pilQ secretin pilT traffic NTPasepilW pilus stabilization protein)

PN Peroxynitritepor PorinpptA Pilin phosphorylcholine transferase APRRs Pattern recognition receptorsPTK Protein tyrosine kinaseRANTES Regulated on activation normal T cell

expressed and secretedRecA Recombinase A


REP2 Repetitive extragenic palindromicsequence

RIG-I Retinoic acid-inducible gene 1rLP2086 Recombinant lipoprotein 2086RLRs RIG-1-like receptorsRNA Ribonucleic acidRNS Reactive nitrogen speciesROS Reactive oxygen speciessia Polysialic acid capsule biosynthesis protein

(siaA siaB siaC siaD)SMAD Small Mothers Against Decapentaplegicsod Superoxide dismutase (sodB sodC)SOMVs Spontaneously released OMVsSSM Slipped strand mispairingSSR Simple Sequence Repeattbp Transferrin-binding proteinTGF Transforming Growth FactorTh T-cell helperTI T-cell IndependentTLR Toll-like receptor (TLR2 TLR4 TLR5

TLR9)TNF Tumor Necrosis FactortspA T cell stimulating protein AUK United KingdomUSA United States of AmericaUTR Untranslated Regionw WeekWGS Whole-genome sequencingWNT Wingless-related integration sitey YearznuD Zinc uptake component D

Conflict of Interests

R Gasparini D Panatto N L Bragazzi P L Lai A BechiniM Levi P Durando and D Amicizia declare that they haveno conflict of interests regarding the publication of this paper

Acknowledgments

Although efforts to make a systematic overview have beenmade as much as possible quoting the relevant scholarlyliterature due to the interdisciplinary nature of the topic andits vastity the authors apologize if they have missed someimportant contributions The authors thank Dr BernardPatrick for revising the paper

References

[1] MMurakami TOhtake RADorschner B Schittek CGarbeand R L Gallo ldquoCathelicidin anti-microbial peptide expressionin sweat an innate defense system for the skinrdquo Journal ofInvestigative Dermatology vol 119 no 5 pp 1090ndash1095 2002

[2] D R Drake K A Brogden D V Dawson and P W WertzldquoThematic review series skin lipids Antimicrobial lipids at theskin surfacerdquo Journal of Lipid Research vol 49 no 1 pp 4ndash112008

[3] R Medzhitov and C Janeway Jr ldquoInnate immunityrdquo The NewEngland Journal of Medicine vol 343 no 5 pp 338ndash344 2000

[4] S Galdiero A Falanga M Cantisani et al ldquoMicrobe-Hostinteractions structure and role of Gram-negative bacterialPorinsrdquo Current Protein and Peptide Science vol 13 no 8 pp843ndash854 2012

[5] A Di Donato G F Draetta G Illiano M A Tufano LSommese and F Galdiero ldquoDo porins inhibit the macrophagephagocyting activity by stimulating the adenylate cyclaserdquoJournal of Cyclic Nucleotide and Protein PhosphorylationResearch vol 11 no 2 pp 87ndash97 1986

[6] F Galdiero M A Tufano L Sommese A Folgore and FTedesco ldquoActivation of complement system by porins extractedfrom Salmonella typhimuriumrdquo Infection and Immunity vol 46no 2 pp 559ndash563 1984

[7] P Massari S Ram H Macleod and L M Wetzler ldquoThe roleof porins in neisserial pathogenesis and immunityrdquo Trends inMicrobiology vol 11 no 2 pp 87ndash93 2003

[8] K Takeda and SAkira ldquoToll-like receptors in innate immunityrdquoInternational Immunology vol 17 no 1 pp 1ndash14 2005

[9] F Hayashi K D Smith A Ozinsky et al ldquoThe innate immuneresponse to bacterial flagellin is mediated by Toll-like receptor5rdquo Nature vol 410 no 6832 pp 1099ndash1103 2001

[10] D M Underhill A Aderem F Hayashi et al ldquoThe innateimmune response to bacterial flagellin is mediated by Toll-likereceptor 5rdquo Nature vol 410 no 6832 pp 1099ndash1103 2001

[11] J Faber C U Meyer C Gemmer et al ldquoHuman toll-likereceptor 4 mutations are associated with susceptibility to inva-sive meningococcal disease in infancyrdquoThe Pediatric InfectiousDisease Journal vol 25 no 1 pp 80ndash81 2006

[12] M S Sanders G T J van Well S Ouburg P S J LundbergA M Van Furth and S A Morre ldquoSingle nucleotide poly-morphisms in TLR9 are highly associated with susceptibilityto bacterial meningitis in childrenrdquo Clinical Infectious Diseasesvol 52 no 4 pp 475ndash480 2011

[13] S Akira S Uematsu and O Takeuchi ldquoPathogen recognitionand innate immunityrdquo Cell vol 124 no 4 pp 783ndash801 2006

[14] T-D Kanneganti M Lamkanfi and G Nunez ldquoIntracellularNOD-like receptors in host defense and diseaserdquo Immunity vol27 no 4 pp 549ndash559 2007

[15] A Denes G Lopez-Castejon andD Brough ldquoCaspase-1 is IL-1just the tip of the ICEbergrdquo Cell Death and Disease vol 3 no7 article e338 2012

[16] A W Segal ldquoHow neutrophils kill microbesrdquo Annual Review ofImmunology vol 23 pp 197ndash223 2005

[17] J C Sun S Ugolini and E Vivier ldquoImmunological memorywithin the innate immune systemrdquoThe EMBO Journal vol 33no 12 pp 1295ndash1303 33

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[19] S M Zughaier ldquoNeisseria meningitidis capsular polysaccha-rides induce inflammatory responses via TLR2 and TLR4-MD-2rdquo Journal of Leukocyte Biology vol 89 no 3 pp 469ndash480 2011

[20] C L Sokol G M Barton A G Farr and R Medzhitov ldquoAmechanism for the initiation of allergen-induced T helper type2 responsesrdquoNature Immunology vol 9 no 3 pp 310ndash318 2008

[21] M Merad P Sathe J Helft J Miller and A Mortha ldquoThedendritic cell lineage ontogeny and function of dendritic cellsand their subsets in the steady state and the inflamed settingrdquoAnnual Review of Immunology vol 31 pp 563ndash604 2013

[22] C A Janeway P Travers M Walport et al ImmunobiologyGarland Science New York NY USA 2001


[23] M Pizza and R Rappuoli ldquoNeisseria meningitidis pathogenesisand immunityrdquo Current Opinion in Microbiology vol 23 pp68ndash72 2015

[24] E Del Tordello and D Serruto ldquoFunctional genomics studiesof the human pathogen Neisseria meningitidisrdquo Briefings inFunctional Genomics vol 12 no 4 pp 328ndash340 2013

[25] C Schoen H Tettelin J Parkhill and M Frosch ldquoGenomeflexibility inNeisseriameningitidisrdquoVaccine vol 27 supplement2 pp B103ndashB111 2009

[26] P M Power and E R Moxon ldquoPhase variation and adaptivestrategies of N meningitidis insights into the biology of acommensal and pathogenrdquo in Handbook of MeningococcalDisease Infection Biology Vaccination ClinicalManagementMFrosch and M C J Maiden Eds Wiley-Blackwell 2006

[27] E Rotman and H S Seifert ldquoThe genetics of Neisseria speciesrdquoAnnual Review of Genetics vol 48 no 1 pp 405ndash431 2014

[28] P R Marri M Paniscus N J Weyand et al ldquoGenomesequencing reveals widespread virulence gene exchange amonghuman Neisseria speciesrdquo PLoS ONE vol 5 no 7 Article IDe11835 2010

[29] L A S Snyder S A Jarvis and N J Saunders ldquoCompleteand variant forms of the lsquogonococcal genetic islandrsquo inNeisseriameningitidisrdquoMicrobiology vol 151 no 12 pp 4005ndash4013 2005

[30] B Joseph R F Schwarz B Linke et al ldquoVirulence evolution ofthe human pathogenNeisseriameningitidis by recombination inthe core and accessory genomerdquo PLoS ONE vol 6 no 4 ArticleID e18441 2011

[31] L A Cahoon and H S Seifert ldquoFocusing homologous recom-bination pilin antigenic variation in the pathogenic NeisseriardquoMolecular Microbiology vol 81 no 5 pp 1136ndash1143 2011

[32] M Kawai I Uchiyama and I Kobayashi ldquoGenome comparisonIn Silico in Neisseria suggests integration of filamentous bacte-riophages by their own transposaserdquo DNA Research vol 12 no6 pp 389ndash401 2005

[33] M W J van Passel A van der Ende and A Bart ldquoPlasmiddiversity in neisseriaerdquo Infection and Immunity vol 74 no 8pp 4892ndash4899 2006

[34] Y N Srikhanta K L Fox andM P Jennings ldquoThe phasevarionphase variation of type III DNA methyltransferases controlscoordinated switching in multiple genesrdquo Nature ReviewsMicrobiology vol 8 no 3 pp 196ndash206 2010

[35] M V R Weber H Claus M C J Maiden M Frosch andU Vogel ldquoGenetic mechanisms for loss of encapsulation inpolysialyltransferase-gene-positivemeningococci isolated fromhealthy carriersrdquo International Journal of Medical Microbiologyvol 296 no 7 pp 475ndash484 2006

[36] A van der Ende C T P Hopman and J Dankert ldquoMultiplemechanisms of phase variation of PorA in Neisseria meningi-tidisrdquo Infection and Immunity vol 68 no 12 pp 6685ndash66902000

[37] P Martin K Makepeace S A Hill D W Hood and ER Moxon ldquoMicrosatellite in instability regulates transcriptionfactor binding and gene expressionrdquo Proceedings of the NationalAcademy of Sciences of the United States of America vol 102 no10 pp 3800ndash3804 2005

[38] R Tobes and E Pareja ldquoBacterial repetitive extragenic palin-dromic sequences are DNA targets for Insertion Sequenceelementsrdquo BMC Genomics vol 7 article 62 2006

[39] L Fagnocchi E Pigozzi V Scarlato and I Delany ldquoIn theNadR regulon adhesins and diverse meningococcal functionsare regulated in response to signals in human salivardquo Journal ofBacteriology vol 194 no 2 pp 460ndash474 2012

[40] L A S Snyder S A Butcher and N J Saunders ldquoComparativewhole-genome analyses reveal over 100 putative phase-variablegenes in the pathogenic Neisseria spprdquo Microbiology vol 147no 8 pp 2321ndash2332 2001

[41] A Rytkonen B Albiger P Hansson-Palo et al ldquoNeisseriameningitidis undergoes PilC phase variation and PilE sequencevariation during invasive diseaserdquo Journal of Infectious Diseasesvol 189 no 3 pp 402ndash409 2004

[42] P Martin L Sun D W Hood and E R Moxon ldquoInvolvementof genes of genome maintenance in the regulation of phasevariation frequencies in Neisseria meningitidisrdquo Microbiologyvol 150 no 9 pp 3001ndash3012 2004

[43] A R Richardson and I Stojiljkovic ldquoMismatch repair andthe regulation of phase variation in Neisseria meningitidisrdquoMolecular Microbiology vol 40 no 3 pp 645ndash655 2001

[44] L A S Snyder N J Saunders and W M Shafer ldquoA putativelyphase variable gene (dca) required for natural competence inNeisseria gonorrhoeae but not Neisseria meningitidis is locatedwithin the division cell wall (dcw) gene clusterrdquo Journal ofBacteriology vol 183 no 4 pp 1233ndash1241 2001

[45] P van Ulsen B Adler P Fassler et al ldquoA novel phase-variable autotransporter serine protease AusI of Neisseriameningitidisrdquo Microbes and Infection vol 8 no 8 pp 2088ndash2097 2006

[46] N J Oldfield S Matar F A Bidmos et al ldquoPrevalenceand phase variable expression status of two autotransportersNalP and MspA in carriage and disease isolates of Neisseriameningitidesrdquo PLoS ONE vol 8 no 7 Article ID e69746 2013

[47] M J Warren andM P Jennings ldquoIdentification and characteri-zation of pptA a gene involved in the phase-variable expressionof phosphorylcholine on pili ofNeisseriameningitidisrdquo Infectionand Immunity vol 71 no 12 pp 6892ndash6898 2003

[48] T Davidsen M Bjoslashras E C Seeberg and T Toslashnjum ldquoAntimu-tator role of DNA glycosylase MutY in pathogenic Neisseriaspeciesrdquo Journal of Bacteriology vol 187 no 8 pp 2801ndash28092005

[49] N J Saunders A C Jeffries J F Peden et al ldquoRepeat-associatedphase variable genes in the complete genome sequence ofNeisseria meningitidis strain MC58rdquo Molecular Microbiologyvol 37 no 1 pp 207ndash215 2000

[50] M M E Metruccio E Pigozzi D Roncarati et al ldquoA novelphase variation mechanism in the meningococcus driven bya ligand-responsive repressor and differential spacing of distalpromoter elementsrdquo PLoS Pathogens vol 5 no 12 Article IDe1000710 2009

[51] H L Alexander A W Rasmussen and I Stojiljkovic ldquoIden-tification of Neisseria meningitidis genetic loci involved inthe modulation of phase variation frequenciesrdquo Infection andImmunity vol 72 no 11 pp 6743ndash6747 2004

[52] A Siddique N Buisine and R Chalmers ldquoThe transposon-like correia elements encode numerous strong promoters andprovide a potential new mechanism for phase variation in themeningococcusrdquoPLoSGenetics vol 7 no 1 Article ID e10012772011

[53] M Mazzone E De Gregorio A Lavitola C Pagliarulo PAlifano and P P Di Nocera ldquoWhole-genome organization andfunctional properties of miniature DNA insertion sequencesconserved in pathogenic Neisseriaerdquo Gene vol 278 no 1-2 pp211ndash222 2001

[54] E de Gregorio C Abrescia M S Carlomagno and P Pdi Nocera ldquoAsymmetrical distribution of Neisseria miniature


insertion sequence DNA repeats among pathogenic and non-pathogenic Neisseria strainsrdquo Infection and Immunity vol 71no 7 pp 4217ndash4221 2003

[55] R Hilse S Hammerschmidt W Bautsch and M FroschldquoSite-specific insertion of IS1301 and distribution in Neisseriameningitidis strainsrdquo Journal of Bacteriology vol 178 no 9 pp2527ndash2532 1996

[56] E Kugelberg B Gollan C Farrance et al ldquoThe influence ofIS 1301 in the capsule biosynthesis locus on meningococcalcarriage and diseaserdquo PLoS ONE vol 5 no 2 Article ID e94132010

[57] J Kiss Z Nagy G Toth et al ldquoTransposition and targetspecificity of the typical IS30 family element IS1655 fromNeisseria meningitidisrdquo Molecular Microbiology vol 63 no 6pp 1731ndash1747 2007

[58] H Tettelin N J Saunders J Heidelberg et al ldquoCompletegenome sequence of Neisseria meningitidis serogroup B strainMC58rdquo Science vol 287 no 5459 pp 1809ndash1815 2000

[59] M Alamro F A Bidmos H Chan et al ldquoPhase variationmediates reductions in expression of surface proteins duringpersistentmeningococcal carriagerdquo Infection and Immunity vol82 no 6 pp 2472ndash2484 2014

[60] M P Jennings Y N Srikhanta E R Moxon et al ldquoThe geneticbasis of the phase variation repertoire of lipopolysaccharideimmunotypes in Neisseria meningitidisrdquoMicrobiology vol 145no 11 pp 3013ndash3021 1999

[61] P M Power L F Roddam M Dieckelmann et al ldquoGeneticcharacterization of pilin glycosylation inNeisseriameningitidisrdquoMicrobiology vol 146 no 4 pp 967ndash979 2000

[62] P M Power L F Roddam K Rutter S Z Fitzpatrick Y NSrikhanta andM P Jennings ldquoGenetic characterization of pilinglycosylation and phase variation in Neisseria meningitidisrdquoMolecular Microbiology vol 49 no 3 pp 833ndash847 2003

[63] M M Estabrook N C Christopher J M Griffiss C J Bakerand R E Mandrell ldquoSialylation and human neutrophil killingof group C Neisseria meningitidisrdquo The Journal of InfectiousDiseases vol 166 no 5 pp 1079ndash1088 1992

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[65] H Claus R Borrow M Achtman et al ldquoGenetics of capsuleO-acetylation in serogroup C W-135 and Y meningococcirdquoMolecular Microbiology vol 51 no 1 pp 227ndash239 2004

[66] P C Fusco E K Farley C-H Huang S Moore and F MichonldquoProtective meningococcal capsular polysaccharide epitopesand the role of O acetylationrdquoClinical and Vaccine Immunologyvol 14 no 5 pp 577ndash584 2007

[67] A Batista-Duharte B Tellez M Tamayo et al ldquoIn Silicoidentification of molecular mimicry between T-cell epitopesof Neisseria meningitidis B and the human proteomerdquo RevistaPeruana de Medicina Experimental y Salud Publica vol 30 no3 pp 441ndash445 2013

[68] J Finne U Finne H Deagostini-Bazin and C GoridisldquoOccurrence of 1205722-8 linked polysialosyl units in a neuralcell adhesion moleculerdquo Biochemical and Biophysical ResearchCommunications vol 112 no 2 pp 482ndash487 1983

[69] G R Moe and D M Granoff ldquoMolecular mimetics of Neis-seria meningitidis serogroup B polysacchariderdquo InternationalReviews of Immunology vol 20 no 2 pp 201ndash220 2001

[70] R E Mandrell and M A Apicella ldquoLipo-oligosaccharides(LOS) of mucosal pathogens molecular mimicry and host-modification of LOSrdquo Immunobiology vol 187 no 3ndash5 pp 382ndash402 1993

[71] A P Moran M M Prendergast and B J Appelmelk ldquoMolecu-lar mimicry of host structures by bacterial lipopolysaccharidesand its contribution to diseaserdquo FEMS Immunology andMedicalMicrobiology vol 16 no 2 pp 105ndash115 1996

[72] HAHarveyW E Swords andMAApicella ldquoThemimicry ofhuman glycolipids and glycosphingolipids by the lipooligosac-charides of pathogenic Neisseria and Haemophilusrdquo Journal ofAutoimmunity vol 16 no 3 pp 257ndash262 2001

[73] C M Tsai ldquoMolecular mimicry of host structures by lipooligo-saccharides of Neisseria meningitidis characterization of sialy-lated and nonsialylated lacto-N-neotetraose (Galbeta1-4GlcNAcbeta1-3Galbeta1-4Glc) structures in lipooligosac-charides using monoclonal antibodies and specific lectinsrdquoAdvances in Experimental Medicine and Biology vol 491 pp525ndash542 2001

[74] H-C Wang T-P Ko M-L Wu S-C Ku H-J Wu and A H-J Wang ldquoNeisseria conserved protein DMP19 is a DNA mimicprotein that prevents DNA binding to a hypothetical nitrogen-response transcription factorrdquo Nucleic Acids Research vol 40no 12 pp 5718ndash5730 2012

[75] M Coureuil G Mikaty F Miller et al ldquoMeningococcal type IVpili recruit the polarity complex to cross the brain endotheliumrdquoScience vol 325 no 5936 pp 83ndash87 2009

[76] F Miller G Phan T Brissac et al ldquoThe hypervariable region ofmeningococcal major pilin PilE controls the host cell responsevia antigenic variationrdquomBio vol 5 no 1 Article ID e01024-132013

[77] M P Bos B Tefsen P Voet V Weynants J P M Van Puttenand J Tommassen ldquoFunction of neisserial outer membranephospholipase A in autolysis and assessment of its vaccinepotentialrdquo Infection and Immunity vol 73 no 4 pp 2222ndash22312005

[78] I W Devoe and J E Gilchrist ldquoRelease of endotoxin in theform of cell wall blebs during in vitro growth of Neisseriameningitidisrdquo Journal of Experimental Medicine vol 138 no 5pp 1156ndash1167 1973

[79] J S Swartley A A Marfin S Edupuganti et al ldquoCapsuleswitching of Neisseria meningitidisrdquo Proceedings of the NationalAcademy of Sciences of the United States of America vol 94 no1 pp 271ndash276 1997

[80] TM P P Castineiras D E Barroso JWMarsh et al ldquoCapsularswitching in invasive Neisseria meningitidis Brazilrdquo EmergingInfectious Diseases vol 18 no 8 pp 1336ndash1338 2012

[81] P Stefanelli C Fazio A Neri T Sofia and P MastrantonioldquoFirst report of capsule replacement among electrophoretic type37 Neisseria meningitidis strains in Italyrdquo Journal of ClinicalMicrobiology vol 41 no 12 pp 5783ndash5786 2003

[82] R S W Tsang D K S Law S D Tyler G S Stephens MBigham andW D Zollinger ldquoPotential capsule switching fromserogroup Y to B the characterization of three such Neisseriameningitidis isolates causing invasive meningococcal disease inCanadardquo Canadian Journal of Infectious Diseases and MedicalMicrobiology vol 16 no 3 pp 171ndash174 2005

[83] L M Hollanda G C G Cury R F C Pereira et al ldquoEffect ofmesoporous silica under Neisseria meningitidis transformationprocess environmental effects under meningococci transfor-mationrdquo Journal of Nanobiotechnology vol 9 article 28 2011


[84] I B Mattos D A Alves L M Hollanda H J CeragiogliV Baranauskas and M Lancellotti ldquoEffects of multi-walledcarbon nanotubes (MWCNT) under Neisseria meningitidistransformation processrdquo Journal of Nanobiotechnology vol 9article 53 2011

[85] U Vogel M-K Taha J A Vazquez et al ldquoPredicted strain cov-erage of a meningococcal multicomponent vaccine (4CMenB)in Europe a qualitative and quantitative assessmentrdquoTheLancetInfectious Diseases vol 13 no 5 pp 416ndash425 2013

[86] A J Beddek M-S Li J S Kroll TW Jordan and D RMartinldquoEvidence for capsule switching between carried and disease-causing Neisseria meningitidis strainsrdquo Infection and Immunityvol 77 no 7 pp 2989ndash2994 2009

[87] L H Harrison K A Shutt S E Schmink et al ldquoPopulationstructure and capsular switching of invasive Neisseria meningi-tidis isolates in the pre-meningococcal conjugate vaccine eramdashUnited States 2000ndash2005rdquo Journal of Infectious Diseases vol201 no 8 pp 1208ndash1224 2010

[88] P van der Ley L Steeghs H J Hamstra J Ten Hove B Zomerand L Van Alphen ldquoModification of lipid a biosynthesis inNeisseria meningitidis lpxL mutants influence on lipopolysac-charide structure toxicity and adjuvant activityrdquo Infection andImmunity vol 69 no 10 pp 5981ndash5990 2001

[89] J C Dunning Hotopp R Grifantini N Kumar et al ldquoCompar-ative genomics ofNeisseriameningitidis core genome islands ofhorizontal transfer and pathogen-specific genesrdquoMicrobiologyvol 152 no 12 pp 3733ndash3749 2006

[90] H Lo C M Tang and R M Exley ldquoMechanisms of avoidanceof host immunity by Neisseria meningitidis and its effect onvaccine developmentrdquoThe Lancet Infectious Diseases vol 9 no7 pp 418ndash427 2009

[91] M C Schneider B E Prosser J J E Caesar et al ldquoNeisseriameningitidis recruits factor H using protein mimicry of hostcarbohydratesrdquo Nature vol 458 no 7240 pp 890ndash893 2009

[92] M Lappann S Danhof F Guenther S Olivares-Florez I LMordhorst and U Vogel ldquoIn vitro resistance mechanisms ofNeisseria meningitidis against neutrophil extracellular trapsrdquoMolecular Microbiology vol 89 no 3 pp 433ndash449 2013

[93] M Stork J Grijpstra M P Bos et al ldquoZinc piracy as amechanism of Neisseria meningitidis for evasion of nutritionalimmunityrdquo PLoS Pathogens vol 9 no 10 Article ID e10037332013

[94] M Saleem S M Prince S E J Rigby et al ldquoUse of a moleculardecoy to segregate transport from antigenicity in the FrpB irontransporter from Neisseria meningitidesrdquo PLoS ONE vol 8 no2 Article ID e56746 2013

[95] K Hubert M-C Pawlik H Claus H Jarva S Meri andU Vogel ldquoOpc expression LPS immunotype switch and pilinconversion contribute to serum resistance of unencapsulatedmeningococcirdquo PLoS ONE vol 7 no 9 Article ID e45132 2012

[96] C M Tsai R Boykins and C E Frasch ldquoHeterogeneity andvariation among Neisseria meningitidis lipopolysaccharidesrdquoJournal of Bacteriology vol 155 no 2 pp 498ndash504 1983

[97] J Chamot-Rooke G Mikaty C Malosse et al ldquoPosttrans-lational modification of pili upon cell contact triggers Nmeningitidis disseminationrdquo Science vol 331 no 6018 pp 778ndash782 2011

[98] F E-C Jen C E Jones J C Wilson B L Schulz and MP Jennings ldquoSubstrate recognition of a structure motif forphosphorylcholine post-translational modification in Neisseriameningitidisrdquo Biochemical and Biophysical Research Communi-cations vol 431 no 4 pp 808ndash814 2013

[99] E Loh E Kugelberg A Tracy et al ldquoTemperature triggersimmune evasion byNeisseria meningitidisrdquoNature vol 502 no7470 pp 237ndash240 2013

[100] M F Anjum T M Stevanin R C Read and J W B MoirldquoNitric oxide metabolism in Neisseria meningitidisrdquo Journal ofBacteriology vol 184 no 11 pp 2987ndash2993 2002

[101] P Stefanelli G Colotti A Neri et al ldquoMolecular characteriza-tion of nitrite reductase gene (aniA) and gene product in Neis-seria meningitidis isolates is aniA essential for meningococcalsurvivalrdquo IUBMB Life vol 60 no 9 pp 629ndash636 2008

[102] H Echenique-Rivera A Muzzi E del Tordello et al ldquoTran-scriptome analysis of Neisseria meningitidis in human wholeblood and mutagenesis studies identify virulence factorsinvolved in blood survivalrdquo PLoS Pathogens vol 7 no 5 ArticleID e1002027 2011

[103] H A Hadi K G Wooldridge K Robinson and D A AAlarsquoAldeen ldquoIdentification and characterization of App animmunogenic autotransporter protein of Neisseria meningi-tidisrdquoMolecular Microbiology vol 41 no 3 pp 611ndash623 2001

[104] J Arenas S Cano R Nijland et al ldquoThe meningococcalautotransporter AutA is implicated in autoaggregation andbiofilm formationrdquo Environmental Microbiology vol 17 no 4pp 1321ndash1337 2015

[105] N H Chen R M Counago K Y Djoko et al ldquoA glutathione-dependent detoxification system is required for formaldehyderesistance and optimal survival of neisseria meningitidis inbiofilmsrdquo Antioxidants and Redox Signaling vol 18 no 7 pp743ndash755 2013

[106] R B Neil and M A Apicella ldquoRole of HrpA in biofilm for-mation of Neisseria meningitidis and regulation of the hrpBAStranscriptsrdquo Infection and Immunity vol 77 no 6 pp 2285ndash2293 2009

[107] A J Potter S P Kidd M P Jennings and A G McEwanldquoEvidence for distinctive mechanisms of S-nitrosoglutathionemetabolism by AdhC in two closely related species Neisseriagonorrhoeae and Neisseria meningitidisrdquo Infection and Immu-nity vol 75 no 3 pp 1534ndash1536 2007

[108] K Yi A W Rasmussen S K Gudlavalleti D S Stephensand I Stojiljkovic ldquoBiofilm formation byNeisseriameningitidisrdquoInfection and Immunity vol 72 no 10 pp 6132ndash6138 2004

[109] S Agarwal S Vasudhev R B DeOliveira and S Ram ldquoInhibi-tion of the classical pathway of complement by meningococcalcapsular polysaccharidesrdquoThe Journal of Immunology vol 193no 4 pp 1855ndash1863 2014

[110] A C Pridmore D H Wyllie F Abdillahi et al ldquoAlipopolysaccharide-deficient mutant of Neisseria meningitidiselicits attenuated cytokine release by human macrophages andsignals via toll-like receptor (TLR) 2 but not via TLR

4MD2rdquo

The Journal of Infectious Diseases vol 183 no 1 pp 89ndash962001

[111] L M Willis and C Whitfield ldquoKpsC and KpsS are retain-ing 3-deoxy-D-manno-oct-2- ulosonic acid (Kdo) transferasesinvolved in synthesis of bacterial capsulesrdquo Proceedings of theNational Academy of Sciences of the United States of Americavol 110 no 51 pp 20753ndash20758 2013

[112] T R Sampson and D S Weiss ldquoCRISPR-Cas systems newplayers in gene regulation and bacterial physiologyrdquo Frontiersin Cellular and Infection Microbiology vol 4 p 37 2014

[113] K M Esvelt P Mali J L Braff M Moosburner S J Yaungand G M Church ldquoOrthogonal Cas9 proteins for RNA-guidedgene regulation and editingrdquoNature Methods vol 10 no 11 pp1116ndash1123 2013


[114] E Kugelberg B Gollan and C M Tang ldquoMechanisms in Neis-seria meningitidis for resistance against complement-mediatedkillingrdquo Vaccine vol 26 supplement 8 pp I34ndashI39 2008

[115] A E Deghmane D Giorgini M Larribe J-M Alonso andM-K Taha ldquoDown-regulation of pili and capsule of Neisseriameningitidis upon contact with epithelial cells is mediated byCrgA regulatory proteinrdquo Molecular Microbiology vol 43 no6 pp 1555ndash1564 2002

[116] R Ieva C Alaimo I Delany G Spohn R Rappuoli and VScarlato ldquoCrgA is an inducible LysR-type regulator of Neisseriameningitidis acting both as a repressor and as an activator ofgene transcriptionrdquo Journal of Bacteriology vol 187 no 10 pp3421ndash3430 2005

[117] K O Johswich J Zhou D K S Law et al ldquoInvasive potentialof nonencapsulated disease isolates of Neisseria meningitidesrdquoInfection and Immunity vol 80 no 7 pp 2346ndash2353 2012

[118] M J Uria Q Zhang Y Li et al ldquoA generic mechanism in Neis-seria meningitidis for enhanced resistance against bactericidalantibodiesrdquo Journal of Experimental Medicine vol 205 no 6pp 1423ndash1434 2008

[119] T M Stevanin J R Laver R K Poole J W B Moir and RC Read ldquoMetabolism of nitric oxide by Neisseria meningitidismodifies release of NO-regulated cytokines and chemokines byhuman macrophagesrdquo Microbes and Infection vol 9 no 8 pp981ndash987 2007

[120] T M Stevanin J W B Moir and R C Read ldquoNitric oxidedetoxification systems enhance survival of Neisseria meningi-tidis in human macrophages and in nasopharyngeal mucosardquoInfection and Immunity vol 73 no 6 pp 3322ndash3329 2005

[121] T Davidsen E K Amundsen E A Roslashdland and T ToslashnjumldquoDNA repair profiles of disease-associated isolates of NeisseriameningitidisrdquoFEMS Immunology andMedicalMicrobiology vol49 no 2 pp 243ndash251 2007

[122] A K Criss and H S Seifert ldquoA bacterial siren song intimateinteractions betweenNeisseria andneutrophilsrdquoNature ReviewsMicrobiology vol 10 no 3 pp 178ndash190 2012

[123] S Schielke C Spatz R F Schwarz et al ldquoCharacterizationof FarR as a highly specialized growth phase-dependent tran-scriptional regulator in Neisseria meningitidisrdquo InternationalJournal of Medical Microbiology vol 301 no 4 pp 325ndash3332011

[124] J Kortekaas S AMuller P Ringler et al ldquoImmunogenicity andstructural characterisation of an in vitro folded meningococcalsiderophore receptor (FrpB FetA)rdquoMicrobes and Infection vol8 no 8 pp 2145ndash2153 2006

[125] J Kortekaas A Pettersson J van der Biezen et al ldquoShieldingof immunogenic domains inNeisseria meningitidis FrpB (FetA)by the major variable regionrdquo Vaccine vol 25 no 1 pp 72ndash842007

[126] K O Mironov A E Platonov I S Koroleva et al ldquoMonitoringfor Neisseria meningitidis species using sequencing of variablefragments of surface proteins FetA and PorA genesrdquo ZhurnalMikrobiologii Epidemiologii i Immunobiologii no 3 pp 23ndash272009

[127] J A Welsch and S Ram ldquoFactor H andNeisserial pathogenesisrdquoVaccine vol 26 no 8 pp I40ndashI45 2008

[128] P van der Ley J van der Biezen R Sutmuller P Hoogerhoutand J T Poolman ldquoSequence variability of FrpB a major iron-regulated outer-membrane protein in the pathogenic neisse-riaerdquoMicrobiology vol 142 no 11 pp 3269ndash3274 1996

[129] I Delany R Rappuoli and V Scarlato ldquoFur functions as anactivator and as a repressor of putative virulence genes in

Neisseria meningitidisrdquo Molecular Microbiology vol 52 no 4pp 1081ndash1090 2004

[130] H Takahashi K Hirose and H Watanabe ldquoNecessity ofmeningococcal 120574-glutamyl aminopeptidase for Neisseriameningitidis growth in rat cerebrospinal fluid (CSF) andCSF-like mediumrdquo Journal of Bacteriology vol 186 no 1 pp244ndash247 2004

[131] A W Rasmussen H L Alexander D Perkins-Balding W MShafer and I Stojiljkovic ldquoResistance of Neisseria meningitidisto the toxic effects of heme iron and other hydrophobic agentsrequires expression of ghtrdquo Journal of Bacteriology vol 187 no15 pp 5214ndash5223 2005

[132] F Putker A Grutsch J Tommassen and M P Bos ldquoGhtprotein of neisseria meningitidis is involved in the regulationof lipopolysaccharide biosynthesisrdquo Journal of Bacteriology vol196 no 4 pp 780ndash789 2014

[133] R Colicchio S Ricci F Lamberti et al ldquoThe meningococcalABC-type L-glutamate transporter GltT is necessary for thedevelopment of experimental meningitis in micerdquo Infection andImmunity vol 77 no 9 pp 3578ndash3587 2009

[134] A Tala C Monaco K Nagorska et al ldquoGlutamate utilizationpromotes meningococcal survival in vivo through avoidance ofthe neutrophil oxidative burstrdquoMolecular Microbiology vol 81no 5 pp 1330ndash1342 2011

[135] C S Hong W Hashimoto A M Fialho T K Das Gupta andA M Chakrabarty ldquoDisrupting the entry barrier and attackingbrain tumors the role of the Neisseria H8 epitope and the Lazproteinrdquo Cell Cycle vol 5 no 15 pp 1633ndash1641 2006

[136] W Baehr E C Gotschlich and P J Hitchcock ldquoThe virulence-associated gonococcal H8 gene encodes 14 tandemly repeatedpentapeptidesrdquoMolecular Microbiology vol 3 no 1 pp 49ndash551989

[137] J R Black W J Black and J G Cannon ldquoNeisserial antigenH8 is immunogenic in patients with disseminated gonococcaland meningococcal infectionsrdquo Journal of Infectious Diseasesvol 151 no 4 pp 650ndash657 1985

[138] T D Ray L A Lewis S Gulati P A Rice and S Ram ldquoNovelblocking human IgG directed against the pentapeptide repeatmotifs of Neisseria meningitidis LipH8 and Laz lipoproteinsrdquoJournal of Immunology vol 186 no 8 pp 4881ndash4894 2011

[139] I Tauseef O B Harrison K G Wooldridge et al ldquoInfluence ofthe combination and phase variation status of the haemoglobinreceptors HmbR and HpuAB on meningococcal virulencerdquoMicrobiology vol 157 no 5 pp 1446ndash1456 2011

[140] J Lucidarme J FindlowHChan et al ldquoThedistribution and lsquoinvivorsquo phase variation status of haemoglobin receptors in invasivemeningococcal serogroup B disease genotypic and phenotypicanalysisrdquo PLoS ONE vol 8 no 9 Article ID e76932 2013

[141] H Omer G Rose K A Jolley et al ldquoGenotypic and pheno-typic modifications of Neisseria meningitidis after an accidentalhuman passagerdquo PLoSONE vol 6 no 2 Article ID e17145 2011

[142] L Fantappie M M E Metruccio K L Seib et al ldquoThe RNAchaperone Hfq is involved in stress response and virulence inNeisseria meningitidis and is a pleiotropic regulator of proteinexpressionrdquo Infection and Immunity vol 77 no 5 pp 1842ndash1853 2009

[143] S Vitovski R C Read and J R Sayers ldquoInvasive isolates ofNeisseria meningitidis possess enhanced immunoglobulin A1protease activity compared to colonizing strainsrdquo The FASEBJournal vol 13 no 2 pp 331ndash337 1999


[144] S A Spence V L Clark and VM Isabella ldquoThe role of catalasein gonococcal resistance to peroxynitriterdquo Microbiology vol158 no 2 pp 560ndash570 2012

[145] H-J Wu K L Seib J L Edwards M A Apicella A GMcEwan and M P Jennings ldquoAzurin of pathogenic Neisseriaspp is involved in defense against hydrogen peroxide andsurvival within cervical epithelial cellsrdquo Infection and Immunityvol 73 no 12 pp 8444ndash8448 2005

[146] V Roussel-Jazede I Jongerius M P Bos J Tommassen andP Van Ulsen ldquoNalP-mediated proteolytic release of lactoferrin-binding protein B from the meningococcal cell surfacerdquo Infec-tion and Immunity vol 78 no 7 pp 3083ndash3089 2010

[147] R Exley M Winterbotham Q Zhang V Pelicic and C MTang ldquoA Conserved Major Pilin subunit in Neisseria meningi-tidisrdquo httpwwwmeningitisorgassetsx52309

[148] S A Brown K L Palmer andMWhiteley ldquoRevisiting the hostas a growth mediumrdquo Nature Reviews Microbiology vol 6 no9 pp 657ndash666 2008

[149] S Piek Z Wang J Ganguly et al ldquoThe role of oxidoreductasesin determining the function of the neisserial lipid a phospho-ethanolamine transferase required for resistance to polymyxinrdquoPLoS ONE vol 9 no 9 Article ID e106513 2014

[150] R SWTsangDK S LawC-MTsai andL-KNg ldquoDetectionof the 1st gene in different serogroups and LOS immunotypes ofNeisseria meningitidisrdquo FEMS Microbiology Letters vol 199 no2 pp 203ndash206 2001

[151] N J Griffiths D J Hill E Borodina et al ldquoMeningococcal sur-face fibril (Msf) binds to activated vitronectin and inhibits theterminal complement pathway to increase serum resistancerdquoMolecular Microbiology vol 82 no 5 pp 1129ndash1149 2011

[152] M K Bielecka N Devos M Gilbert et al ldquoRecombinantprotein truncation strategy for inducing bactericidal antibodiesto the macrophage infectivity potentiator protein of Neisseriameningitidis and circumventing potential cross-reactivity withhuman FK506-binding proteinsrdquo Infection and Immunity vol83 no 2 pp 730ndash742 2015

[153] N Tsolakos C Brookes S Taylor et al ldquoIdentification ofvaccine antigens using integrated proteomic analyses of surfaceimmunogens from serogroup B Neisseria meningitidisrdquo Journalof Proteomics vol 101 pp 63ndash76 2014

[154] Y-L Tzeng A Datta K Ambrose et al ldquoThe MisRMisS two-component regulatory system influences inner core structureand immunotype of lipooligosaccharide in Neisseria meningi-tidisrdquo The Journal of Biological Chemistry vol 279 no 33 pp35053ndash35062 2004

[155] J Adu-Bobie P Lupetti B Brunelli et al ldquoGNA33 of Neisseriameningitidis is a lipoprotein required for cell separation mem-brane architecture and virulencerdquo Infection and Immunity vol72 no 4 pp 1914ndash1919 2004

[156] K L Seib H-J Tseng A G McEwan M A Apicella andM P Jennings ldquoDefenses against oxidative stress in Neisseriagonorrhoeae and Neisseria meningitidis distinctive systems fordifferent lifestylesrdquo The Journal of Infectious Diseases vol 190no 1 pp 136ndash147 2004

[157] M Antoine A Gand S Boschi-Muller andG Branlant ldquoChar-acterization of the amino acids from Neisseria meningitidisMsrA involved in the chemical catalysis of the methioninesulfoxide reduction steprdquo The Journal of Biological Chemistryvol 281 no 51 pp 39062ndash39070 2006

[158] Y-L Tzeng K D Ambrose S Zughaier et al ldquoCationic antimi-crobial peptide resistance in Neisseria meningitidisrdquo Journal ofBacteriology vol 187 no 15 pp 5387ndash5396 2005

[159] R M Delahay B D Robertson J T Balthazar W M Shaferand C A Ison ldquoInvolvement of the gonococcal MtrE proteinin the resistance of Neisseria gonorrhoeae to toxic hydrophobicagentsrdquoMicrobiology vol 143 no 7 pp 2127ndash2133 1997

[160] M Comanducci S Bambini B Brunelli et al ldquoNadA a novelvaccine candidate of Neisseria meningitidisrdquo The Journal ofExperimental Medicine vol 195 no 11 pp 1445ndash1454 2002

[161] B Capecchi J Adu-Bobie F di Marcello et al ldquoNeisseriameningitidis NadA is a new invasin which promotes bacterialadhesion to and penetration into human epithelial cellsrdquoMolec-ular Microbiology vol 55 no 3 pp 687ndash698 2005

[162] C Mazzon B Baldani-Guerra P Cecchini et al ldquoIFN-120574and R-848 dependent activation of human monocyte-deriveddendritic cells byNeisseria meningitidis adhesin ArdquoThe Journalof Immunology vol 179 no 6 pp 3904ndash3916 2007

[163] G Bozza M Capitani P Montanari et al ldquoRole of ARF6Rab11 and external Hsp90 in the trafficking and recycling ofrecombinant-soluble neisseria meningitidis adhesin A (rNadA)in human epithelial cellsrdquo PLoS ONE vol 9 no 10 Article IDe110047 2014

[164] V Nagele J Heesemann S Schielke L F Jimenez-Soto OKurzai and N Ackermann ldquoNeisseria meningitidis adhesinNadA targets beta1 integrins functional similarity to Yersiniainvasionrdquo The Journal of Biological Chemistry vol 286 no 23pp 20536ndash20546 2011

[165] S Franzoso C Mazzon M Sztukowska et al ldquoHumanmonocytesmacrophages are a target of Neisseria meningitidisAdhesin A (NadA)rdquo Journal of Leukocyte Biology vol 83 no 5pp 1100ndash1110 2008

[166] P van Ulsen L van Alphen J ten Hove F Fransen Pvan der Ley and J Tommassen ldquoA Neisserial autotransporterNalP modulating the processing of other autotransportersrdquoMolecular Microbiology vol 50 no 3 pp 1017ndash1030 2003

[167] S Bambini J Piet A Muzzi et al ldquoAn analysis of the sequencevariability of meningococcal fHbp NadA andNHBA over a 50-year period in the Netherlandsrdquo PLoS ONE vol 8 no 5 ArticleID e65043 2013

[168] I R Peak Y N Srikhanta V E Weynants C Feron J TPoolman and M P Jennings ldquoEvaluation of truncated NhhAprotein as a candidate meningococcal vaccine antigenrdquo PLoSONE vol 8 no 9 Article ID e72003 2013

[169] H Sjolinder and A-B Jonsson ldquoImaging of disease dynamicsduring meningococcal sepsisrdquo PLoS ONE vol 2 no 2 articlee241 2007

[170] K R Barth V M Isabella and V L Clark ldquoBiochemicaland genomic analysis of the denitrification pathway within thegenus Neisseriardquo Microbiology vol 155 no 12 pp 4093ndash41032009

[171] M Aspholm F E Aas O B Harrison et al ldquoStructural alter-ations in a component of cytochrome c oxidase and molecularevolution of pathogenic Neisseria in humansrdquo PLoS Pathogensvol 6 no 8 Article ID e1001055 pp 55ndash56 2010

[172] J R Laver T M Stevanin S L Messenger et al ldquoBacterialnitric oxide detoxification prevents host cell S-nitrosothiolformation a novel mechanism of bacterial pathogenesisrdquo TheFASEB Journal vol 24 no 1 pp 286ndash295 2010

[173] S Chandra D Singh and T R Singh ldquoPrediction and char-acterization of T-cell epitopes for epitope vaccine design fromouter membrane protein ofNeisseria meningitidis serogroup BrdquoBioinformation vol 5 no 4 pp 155ndash161 2010

[174] S Giuntini D M Vu and D M Granoff ldquoFH-dependentcomplement evasion by disease-causing meningococcal strains


with absent fHbp genes or frameshift mutationsrdquo Vaccine vol31 no 38 pp 4192ndash4199 2013

[175] L A Lewis D M Vu D M Granoff and S Ram ldquoInhibitionof the alternative pathway of nonhuman infant complement byporin B2 contributes to virulence of Neisseria meningitidis inthe infant rat modelrdquo Infection and Immunity vol 82 no 6 pp2574ndash2584 2014

[176] J D Rock M J Thomson R C Read and J W B MoirldquoRegulation of denitrification genes inNeisseria meningitidis bynitric oxide and the repressorNsrRrdquo Journal of Bacteriology vol189 no 3 pp 1138ndash1144 2007

[177] K Heurlier M J Thomson N Aziz and J W B MoirldquoThe nitric oxide (NO)-sensing repressor NsrR of Neisseriameningitidis has a compact regulon of genes involved in NOsynthesis and detoxificationrdquo Journal of Bacteriology vol 190no 7 pp 2488ndash2495 2008

[178] H J Lee B Rakic M Gilbert WWWakarchuk S GWithersandN C J Strynadka ldquoStructural and kinetic characterizationsof the polysialic acidO-acetyltransferaseOatWY fromNeisseriameningitidisrdquo Journal of Biological Chemistry vol 284 no 36pp 24501ndash24511 2009

[179] M Sadarangani A J Pollard and S D Gray-Owen ldquoOpaproteins and CEACAMs pathways of immune engagement forpathogenic Neisseriardquo FEMS Microbiology Reviews vol 35 no3 pp 498ndash514 2011

[180] M J Callaghan C Buckee N D McCarthy et al ldquoOpa proteinrepertoires of disease-causing and carried meningococcirdquo Jour-nal of Clinical Microbiology vol 46 no 9 pp 3033ndash3041 2008

[181] E Carbonnelle D J Hill P Morand et al ldquoMeningococcalinteractions with the hostrdquo Vaccine vol 27 supplement 2 ppB78ndashB89 2009

[182] K O Johswich S E McCaw E Islam et al ldquoIn vivo adaptationand persistence of Neisseria meningitidis within the nasopha-ryngeal mucosardquo PLoS Pathogens vol 9 no 7 Article IDe1003509 2013

[183] H A Rowe N J Griffiths D J Hill and M Virji ldquoCo-ordinateaction of bacterial adhesins and human carcinoembryonicantigen receptors in enhanced cellular invasion by capsulateserum resistant Neisseria meningitidisrdquo Cellular Microbiologyvol 9 no 1 pp 154ndash168 2007

[184] K Wolff and A Stern ldquoIdentification and characterization ofspecific sequences encoding pathogenicity associated proteinsin the genome of commensal Neisseria speciesrdquo FEMSMicrobi-ology Letters vol 125 no 2-3 pp 255ndash263 1995

[185] M M Eason and X Fan ldquoThe role and regulation of catalase inrespiratory tract opportunistic bacterial pathogensrdquo MicrobialPathogenesis vol 74 pp 50ndash58 2014

[186] R Ieva D Roncarati MM EMetruccio K L Seib V Scarlatoand I Delany ldquoOxyR tightly regulates catalase expression inNeisseria meningitidis through both repression and activationmechanismsrdquo Molecular Microbiology vol 70 no 5 pp 1152ndash1165 2008

[187] C Dehio S D Gray-Owen and T F Meyer ldquoHost cell invasionby pathogenicNeisseriaerdquo Sub-Cellular Biochemistry vol 33 pp61ndash96 2000

[188] J P Dillard and K T Hackett ldquoMutations affecting pepti-doglycan acetylation in Neisseria gonorrhoeae and Neisseriameningitidisrdquo Infection and Immunity vol 73 no 9 pp 5697ndash5705 2005

[189] I Linhartova M Basler J Ichikawa et al ldquoMeningococcaladhesion suppresses proapoptotic gene expression and pro-motes expression of genes supporting early embryonic and

cytoprotective signaling of human endothelial cellsrdquo FEMSMicrobiology Letters vol 263 no 1 pp 109ndash118 2006

[190] H Takahashi T Yanagisawa K S Kim S Yokoyama andM Ohnishi ldquoMeningococcal pilV potentiates Neisseria menin-gitidis type IV pilus-mediated internalization into humanendothelial and epithelial cellsrdquo Infection and Immunity vol 80no 12 pp 4154ndash4166 2012

[191] S C Bernard N Simpson O Join-Lambert et al ldquoPathogenicNeisseria meningitidis utilizes CD147 for vascular colonizationrdquoNature Medicine vol 20 no 7 pp 725ndash731 2014

[192] S V Balasingham R F Collins R Assalkhou et al ldquoInter-actions between the lipoprotein PilP and the secretin PilQ inNeisseria meningitidisrdquo Journal of Bacteriology vol 189 no 15pp 5716ndash5727 2007

[193] S K DashM Sharma S Khare andA Kumar ldquormpMGene asa genetic marker for human bacterial meningitisrdquo Cellular andMolecular Biology vol 58 no 1 pp 26ndash30 2012

[194] A Hey M-S Li M J Hudson P R Langford and J SimonKrolla ldquoTranscriptional profiling of Neisseria meningitidisinteracting with human epithelial cells in a long-term in vitrocolonization modelrdquo Infection and Immunity vol 81 no 11 pp4149ndash4159 2013

[195] R Grifantini E Frigimelica I Delany et al ldquoCharacterizationof a novel Neisseria meningitidis Fur and iron-regulated operonrequired for protection from oxidative stress utility of DNAmicroarray in the assignment of the biological role of hypothet-ical genesrdquoMolecular Microbiology vol 54 no 4 pp 962ndash9792004

[196] R Gasparini D Amicizia P L Lai and D Panatto ldquoNeisseriameningitidis pathogeneticmechanisms to overcome the humanimmune defencesrdquo Journal of Preventive Medicine and Hygienevol 53 no 2 pp 50ndash55 2012

[197] A Unkmeir U Kammerer A Stade et al ldquoLipooligosaccha-ride and polysaccharide capsule virulence factors of Neisseriameningitidis that determine meningococcal interaction withhuman dendritic cellsrdquo Infection and Immunity vol 70 no 5pp 2454ndash2462 2002

[198] M R Spinosa C Progida A Tala L Cogli P Alifano andC Bucci ldquoThe Neisseria meningitidis capsule is important forintracellular survival in human cellsrdquo Infection and Immunityvol 75 no 7 pp 3594ndash3603 2007

[199] A Tala L Cogli M D Stefano et al ldquoSerogroup-specific inter-action of Neisseria meningitidis capsular polysaccharide withhost cell microtubules and effects on tubulin polymerizationrdquoInfection and Immunity vol 82 no 1 pp 265ndash274 2014

[200] D J Hill N J Griffiths E Borodina andM Virji ldquoCellular andmolecular biology of Neisseria meningitidis colonization andinvasive diseaserdquo Clinical Science vol 118 no 9 pp 547ndash5642010

[201] M Drogari-Apiranthitou E J Kuijper N Dekker and JDankert ldquoComplement activation and formation of the mem-brane attack complex on serogroup B Neisseria meningitidis inthe presence or absence of serum bactericidal activityrdquo Infectionand Immunity vol 70 no 7 pp 3752ndash3758 2002

[202] S Ram F G Mackinnon S Gulati et al ldquoThe contrastingmechanisms of serum resistance of Neisseria gonorrhoeae andgroup BNeisseria meningitidisrdquoMolecular Immunology vol 36no 13-14 pp 915ndash928 1999

[203] M J Simoes M Cunha F Almeida C Furtado and LBrum ldquoMolecular surveillance of Neisseria meningitidis cap-sular switching in Portugal 2002ndash2006rdquo Epidemiology andInfection vol 137 no 2 pp 161ndash165 2009


[204] L Craig N Volkmann A S Arvai et al ldquoType IV pilusstructure by cryo-electron microscopy and crystallographyimplications for pilus assembly and functionsrdquo Molecular Cellvol 23 no 5 pp 651ndash662 2006

[205] M Kirchner and T F Meyer ldquoThe PilC adhesin of the Neisseriatype IV pilusmdashbinding specificities and new insights into thenature of the host cell receptorrdquoMolecularMicrobiology vol 56no 4 pp 945ndash957 2005

[206] C J Orihuela J Mahdavi J Thornton et al ldquoLaminin receptorinitiates bacterial contact with the blood brain barrier in experi-mental meningitis modelsrdquo Journal of Clinical Investigation vol119 no 6 pp 1638ndash1646 2009

[207] J L Diaz M Virji and J E Heckels ldquoStructural and antigenicdifferences between two types of meningococcal pilirdquo FEMSMicrobiology Letters vol 21 no 2 pp 181ndash184 1984

[208] R A Helm and H S Seifert ldquoFrequency and rate of pilinantigenic variation of Neisseria meningitidisrdquo Journal of Bacte-riology vol 192 no 14 pp 3822ndash3823 2010

[209] M E Wormann C L Horien J S Bennett et al ldquoSequencedistribution and chromosomal context of class I and class IIpilin genes ofNeisseria meningitidis identified in whole genomesequencesrdquo BMC Genomics vol 15 no 1 article 253 2014

[210] E Carbonnelle S Helaine X Nassif and V Pelicic ldquoA sys-tematic genetic analysis in Neisseria meningitidis defines the Pilproteins required for assembly functionality stabilization andexport of type IV pilirdquo Molecular Microbiology vol 61 no 6pp 1510ndash1522 2006

[211] M Kirchner D Heuer and T F Meyer ldquoCD46-independentbinding of neisserial type IV pili and the major pilus adhesinPilC to human epithelial cellsrdquo Infection and Immunity vol 73no 5 pp 3072ndash3082 2005

[212] M Coureuil H Lecuyer M G H Scott et al ldquoMeningococcushijacks a 1205732-adrenoceptor120573-arrestin pathway to cross brainmicrovasculature endotheliumrdquo Cell vol 143 no 7 pp 1149ndash1160 2010

[213] T Brissac G Mikaty G Dumenil M Coureuil and X NassifldquoThe meningococcal minor pilin PilX is responsible for typeIV pilus conformational changes associated with signaling toendothelial cellsrdquo Infection and Immunity vol 80 no 9 pp3297ndash3306 2012

[214] M Virji S MWatt S Barker K Makepeace and R DoyonnasldquoThe N-domain of the human CD66a adhesion molecule is atarget for Opa proteins of Neisseria meningitidis and Neisseriagonorrhoeaerdquo Molecular Microbiology vol 22 no 5 pp 929ndash939 1996

[215] E R Watkins Y H Grad S Gupta and C O Buckee ldquoCon-trasting within- and between-host immune selection shapesNeisseria Opa repertoiresrdquo Scientific Reports vol 4 Article IDe6554 2014

[216] R Leuzzi L Serino D Serruto andM Pizza ldquoNewly describedsurface structures and adhesion strategies of the pathogenicNeisseriaerdquo inNeisseria Molecular Mechanisms of PathogenesisCaister Academic Press Norfolk UK 2010

[217] J Pohlner R Halter and T FMeyer ldquoNeisseria gonorrhoeae IgAprotease Secretion and implications for pathogenesisrdquo Antonievan Leeuwenhoek vol 53 no 6 pp 479ndash484 1987

[218] D P J Turner A G Marietou L Johnston et al ldquoCharac-terization of MspA an immunogenic autotransporter proteinthat mediates adhesion to epithelial and endothelial cells inNeisseria meningitidisrdquo Infection and Immunity vol 74 no 5pp 2957ndash2964 2006

[219] M Sjolinder G Altenbacher M Hagner W Sun S Schedin-Weiss and H Sjolinder ldquoMeningococcal outer membraneprotein NhhA triggers apoptosis in macrophagesrdquo PLoS ONEvol 7 no 1 Article ID e29586 2012

[220] V Nagele J Heesemann S Schielke L F Jimenez-Soto OKurzai and N Ackermann ldquoNeisseria meningitidis adhesinNadA targets 1205731 integrins functional similarity to Yersiniainvasionrdquo The Journal of Biological Chemistry vol 286 no 23pp 20536ndash20546 2011

[221] F S Archibald and M N Duong ldquoSuperoxide dismutase andoxygen toxicity defenses in the genus Neisseriardquo Infection andImmunity vol 51 no 2 pp 631ndash641 1986

[222] S Sainsbury J Ren J E Nettleship N J Saunders D I Stuartand R J Owens ldquoThe structure of a reduced form ofOxyR fromNeisseria meningitidisrdquo BMC Structural Biology vol 10 article10 2010

[223] K E Wilks K L R Dunn J L Farrant et al ldquoPeriplasmicsuperoxide dismutase in meningococcal pathogenicityrdquo Infec-tion and Immunity vol 66 no 1 pp 213ndash217 1998

[224] C Schoen L Kischkies J Elias and B J Ampattu ldquoMetabolismand virulence in Neisseria meningitidisrdquo Frontiers in Cellularand Infection Microbiology vol 4 p 114 2014

[225] J A Gomez M T Criado and C M Ferreiros ldquoCooperationbetween the components of the meningococcal transferrinreceptor TbpA and TbpB in the uptake of transferrin ironby the 37-kDa ferric-binding protein (FbpA)rdquo Research inMicrobiology vol 149 no 6 pp 381ndash387 1998

[226] K L R Dunn J L Farrant P R Langford and J S KrollldquoBacterial [CuZn]-cofactored superoxide dismutase protectsopsonized encapsulated Neisseria meningitidis from phagocy-tosis by human monocytesmacrophagesrdquo Infection and Immu-nity vol 71 no 3 pp 1604ndash1607 2003

[227] R M Exley J Shaw E Mowe et al ldquoAvailable carbon sourceinfluences the resistance of Neisseria meningitidis against com-plementrdquo Journal of Experimental Medicine vol 201 no 10 pp1637ndash1645 2005

[228] D Serruto and C L Galeotti ldquoThe signal peptide sequence ofa lytic transglycosylase of Neisseria meningitidis is involved inregulation of gene expressionrdquoMicrobiology vol 150 no 5 pp1427ndash1437 2004

[229] H Takahashi K S Kim and H Watanabe ldquoMeningococcalinternalization into human endothelial and epithelial cells istriggered by the influx of extracellular L-glutamate via GltT L-glutamate ABC transporter in neisseria meningitidisrdquo Infectionand Immunity vol 79 no 1 pp 380ndash382 2011

[230] M K Pangburn V P Ferreira and C Cortes ldquoDiscriminationbetween host and pathogens by the complement systemrdquoVaccine vol 26 no 8 supplement pp I15ndashI21 2008

[231] IH Lepow L PillemerMD Schoenberg et al ldquoTheproperdinsystem and immunity X Characterization of partially purifiedhuman properdinrdquo Journal of Immunology vol 83 pp 428ndash4361959

[232] N A Cunliffe N Snowden E M Dunbar and M R HaeneyldquoRecurrent meningococcal septicaemia and properdin defi-ciencyrdquo Journal of Infection vol 31 no 1 pp 67ndash68 1995

[233] D Panatto D Amicizia P L Lai and R Gasparini ldquoNeisseriameningitidis B vaccinesrdquo Expert Review of Vaccines vol 10 no9 pp 1337ndash1351 2011

[234] RGasparini DAmicizia ADomnich P L Lai andD PanattoldquoNeisseriameningitidis B vaccines recent advances and possibleimmunization policiesrdquo Expert Review of Vaccines vol 13 no 3pp 345ndash364 2014


[235] D Panatto D Amicizia P L Lai M L Cristina A Domnichand R Gasparini ldquoNew versus old meningococcal Group Bvaccines how the new ones may benefit infants amp toddlersrdquoIndian Journal of Medical Research vol 138 pp 835ndash846 2013

[236] D Male J Brostoff D B Roth et al Immunology MosbyElsevier Toronto Canada 2006

[237] A Gasparoni L Ciardelli A Avanzini et al ldquoAge-relatedchanges in intracellularTh1Th2cytokine production immuno-proliferative T lymphocyte response and natural killer cellactivity in newborns children and adultsrdquo Biology of theNeonate vol 84 no 4 pp 297ndash303 2003

[238] C Hartel N Adam T Strunk P Temming M Muller-Steinhardt and C Schultz ldquoCytokine responses correlate dif-ferentially with age in infancy and early childhoodrdquoClinical andExperimental Immunology vol 142 no 3 pp 446ndash453 2005

[239] B Morein G Blomqvist and K Hu ldquoImmune responsivenessin the neonatal periodrdquo Journal of Comparative Pathology vol137 no 1 pp S27ndashS31 2007

[240] I Goldschneider E C Gotschlich and M S ArtensteinldquoHuman immunity to the meningococcus II Development ofnatural immunityrdquo Journal of Experimental Medicine vol 129no 6 pp 1327ndash1348 1969

[241] S Flexner ldquoThe results of the serum treatment in thirteen hun-dred cases of epidemic meningitisrdquoThe Journal of ExperimentalMedicine vol 17 no 5 pp 553ndash576 1913

[242] V Davenport E Groves C G Hobbs N A Williams and RS Heyderman ldquoRegulation ofTh-1 T cell-dominated immunityto Neisseria meningitidis within the human mucosardquo CellularMicrobiology vol 9 no 4 pp 1050ndash1061 2007

[243] N A Korzhueva D I Rybalko V P Naglenko and A PZinchenko ldquoSpecific immunological reactivity in generalizedforms of meningococcal infection in childrenrdquo Zhurnal Mikro-biologii Epidemiologii i Immunobiologii no 8 pp 110ndash114 1984

[244] S Raziuddin M E-H El-Awad and N A Mir ldquoBacterialmeningitis T cell activation and immunoregulatory CD4+ Tcell subset alterationrdquo Journal of Allergy and Clinical Immunol-ogy vol 87 no 6 pp 1115ndash1120 1991

[245] A J Pollard R Galassini E M Rouppe van der Voort etal ldquoCellular immune responses to Neisseria meningitidis inchildrenrdquo Infection and Immunity vol 67 no 5 pp 2452ndash24631999

[246] A C Cruz B S Figueredo S L Souza M C Rebelo A GCarvalho and L G Milagres ldquoAntibody and memory CD4+ T-cell responses after meningococcal diseaserdquoVaccine vol 32 no40 pp 5145ndash5148 2014

[247] V Davenport T Guthrie J Findlow R Borrow N AWilliamsand R S Heyderman ldquoEvidence for naturally acquired T cell-mediated mucosal immunity to Neisseria meningitidisrdquo TheJournal of Immunology vol 171 no 8 pp 4263ndash4270 2003

[248] E C Gotschlich T Y Liu and M S Artenstein ldquoHumanimmunity to the meningococcus 3 Preparation and immuno-chemical properties of the group A group B and group Cmeningococcal polysaccharidesrdquo The Journal of ExperimentalMedicine vol 129 no 6 pp 1349ndash1365 1969

[249] E C Gotschlich I Goldschneider and M S ArtensteinldquoHuman immunity to the meningococcus IV Immunogenicityof group A and group C meningococcal polysaccharides inhuman volunteersrdquo Journal of Experimental Medicine vol 129no 6 pp 1367ndash1384 1969

[250] E C Gotschlich I Goldschneider and M S ArtensteinldquoMeningococcal infections 2 Field trial of group C meningo-coccal polysaccharide vaccine in 1969-70rdquo Bulletin of the World

Health Organization vol 45 Article ID 196970 pp 279ndash2821971

[251] M S Artenstein ldquoControl of meningococcal meningitis withmeningococcal vaccinesrdquo Yale Journal of Biology and Medicinevol 48 no 3 pp 197ndash200 1975

[252] J F BrundageMAK Ryan BH Feighner and F J ErdtmannldquoMeningococcal disease among United States military servicemembers in relation to routine uses of vaccines with differentserogroup-specific components 1964ndash1998rdquo Clinical InfectiousDiseases vol 35 no 11 pp 1376ndash1381 2002

[253] R Biselli A Fattorossi P M Matricardi R Nisini T Strof-folini and R DrsquoAmelio ldquoDramatic reduction of meningococcalmeningitis amongmilitary recruits in Italy after introduction ofspecific vaccinationrdquo Vaccine vol 11 no 5 pp 578ndash581 1993

[254] World Health Organization ldquoInternational travel and healthlsquoMeningococcal diseasersquordquo httpwwwwhointithdiseasesmen-ingococcalen

[255] K E Stein ldquoThymus-independent and thymus-dependentresponses to polysaccharide antigensrdquo Journal of InfectiousDiseases vol 165 supplement 1 pp S49ndashS52 1992

[256] J I Ward and K M Zangwill ldquoHaemophilus influenzaevaccinesrdquo in Vaccines WB Saunders Philadelphia Pa USA1999

[257] P J Baker ldquoT cell regulation of the antibody response tobacterial polysaccharide antigens an examination of some gen-eral characteristics and their implicationsrdquo Journal of InfectiousDiseases vol 165 supplement pp S44ndashS48 1992

[258] M A Breukels A Zandvoort G P J M van den Dobbelsteenet al ldquoPneumococcal conjugate vaccines overcome splenicdependency of antibody response to pneumococcal polysaccha-ridesrdquo Infection and Immunity vol 69 no 12 pp 7583ndash75872001

[259] C A Siegrist ldquoVaccine immunologyrdquo httpwwwwhointimmunizationdocumentsElsevier Vaccine immunologypdf

[260] European Medicines Agency ldquoNimenrixrdquo httpwwwemaeuropaeudocsen GBdocument libraryEPAR - Public as-sessment reporthuman002226WC500127664pdf

[261] Centers for Disease Control and Prevention ldquoPreventionand control of meningococcal disease recommendations ofthe advisory committee on immunization practices (ACIP)rdquoMorbidity and Mortality Weekly Report vol 62 no 2 2013httpwwwcdcgovmmwrpdfrrrr6202pdf

[262] EuropeanMedicines Agency ldquoMenveordquo httpwwwemaeuropaeudocsen GBdocument libraryEPAR - Public assessmentreporthuman001095WC500090150pdf

[263] D Serruto T Spadafina L Ciucchi et al ldquoNeisseriameningitidisGNA2132 a heparin-binding protein that induces protectiveimmunity in humansrdquo Proceedings of the National Academy ofSciences of the United States of America vol 107 no 8 pp 3770ndash3775 2010

[264] J AWelsch G RMoe R Rossi J Adu-Bobie R Rappuoli andD M Granoff ldquoAntibody to genome-derived neisserial anti-gen 2132 a Neisseria meningitidis candidate vaccine confersprotection against bacteremia in the absence of complement-mediated bactericidal activityrdquo The Journal of Infectious Dis-eases vol 188 no 11 pp 1730ndash1740 2003

[265] J S Plested and D M Granoff ldquoVaccine-induced opsonopha-gocytic immunity to Neisseria meningitidis group Brdquo Clinicaland Vaccine Immunology vol 15 no 5 pp 799ndash804 2008

[266] G Madico J A Welsch L A Lewis et al ldquoThe meningococcalvaccine candidate GNA1870 binds the complement regulatory


protein factor H and enhances serum resistancerdquoThe Journal ofImmunology vol 177 no 1 pp 501ndash510 2006

[267] M C Schneider R M Exley H Chan et al ldquoFunctionalsignificance of factor H binding to Neisseria meningitidisrdquo TheJournal of Immunology vol 176 no 12 pp 7566ndash7575 2006

[268] T Vesikari S Esposito R Prymula et al ldquoImmunogenicityand safety of an investigational multicomponent recombinantmeningococcal serogroup B vaccine (4CMenB) administeredconcomitantly with routine infant and child vaccinationsresults of two randomised trialsrdquoThe Lancet vol 381 no 9869pp 825ndash835 2013

[269] D Toneatto P Oster A C W DeBoer et al ldquoEarly clinicalexperience with a candidate meningococcal B recombinantvaccine (rMenB) in healthy adultsrdquo Human Vaccines vol 7 no7 pp 781ndash791 2011

[270] European Medicines Agency Bexsero European MedicinesAgency London UK 2013 httpwwwemaeuropaeuemaindexjspcurl=pagesmedicineshumanmedicines002333human med 001614jspampmid=WC0b01ac058001d124

[271] Agenzia Italiana del Farmaco Determina 29 luglio 2013 Clas-sificazione del medicinale per uso umano ldquoBexserordquo ai sensidellart 8 comma 10 della legge 24 dicembre 1993 n 537(Determina 6982013) Gazzetta UfficialemdashSerie Generalemdashno194 del 20 agosto 2013

[272] Food and Drug Administration ldquoTrumenbardquo httpwwwfdagovdownloadsBiologicsBloodVaccinesVaccinesApproved-ProductsUCM421139pdf

[273] L D Fletcher L Bernfield V Barniak et al ldquoVaccine Potentialof the Neisseria meningitidis 2086 Lipoproteinrdquo Infection andImmunity vol 72 no 4 pp 2088ndash2100 2004

[274] D Zhu Y Zhang V Barniak L Bernfield A Howell and GZlotnick ldquoEvaluation of recombinant lipidated P2086 proteinas a vaccine candidate for group B Neisseria meningitidis in amurine nasal challenge modelrdquo Infection and Immunity vol 73no 10 pp 6838ndash6845 2005

[275] D Zhu V Barniak Y Zhang B Green and G ZlotnickldquoIntranasal immunization of mice with recombinant lipidatedP2086 protein reduces nasal colonization of group B Neisseriameningitidisrdquo Vaccine vol 24 no 26 pp 5420ndash5425 2006

[276] A S Anderson L Hao Q Jiang et al ldquoPotential impactof the bivalent rLP2806vaccine on Neisseria meningitidis car-riage and invasive serogroup B diseaserdquo Human Vaccines andImmunotherapeutics vol 9 no 3 pp 471ndash479 2013

[277] F Martinon-Torres F Gimenez-Sanchez E Bernaola-IturbeJ Diez-Domingo Q Jiang and J L Perez ldquoA randomizedphase 12 trial of the safety tolerability and immunogenicity ofbivalent rLP2086 meningococcal B vaccine in healthy infantsrdquoVaccine vol 32 no 40 pp 5206ndash5211 2014

[278] H S Marshall P C Richmond M D Nissen et al ldquoAphase 2 open-label safety and immunogenicity study of ameningococcal B bivalent rLP2086 vaccine in healthy adultsrdquoVaccine vol 31 no 12 pp 1569ndash1575 2013

[279] S L Harris D Zhu E Murphy et al ldquoPreclinical evidence forthe potential of a bivalent fHBP vaccine to prevent Neisseriameningitidis serogroup C diseaserdquo Human Vaccines vol 7supplement 1 pp 68ndash74 2011

[280] M Konar D M Granoff and P T Beernink ldquoImportanceof inhibition of binding of complement factor H for serumbactericidal antibody responses to meningococcal factor H-binding protein vaccinesrdquoThe Journal of Infectious Diseases vol208 no 4 pp 627ndash636 2013

[281] L Lemee E Hong M Etienne et al ldquoGenetic diversity andlevels of expression of factor H binding protein among carriageisolates of Neisseria meningitidisrdquo PLoS ONE vol 9 no 9Article ID e107240 2014

[282] M Delgado D Yero O Niebla et al ldquoLipoprotein NMB0928from Neisseria meningitidis serogroup B as a novel vaccinecandidaterdquo Vaccine vol 25 no 50 pp 8420ndash8431 2007

[283] C-A Hsu W-R Lin J-C Li et al ldquoImmunoproteomicidentification of the hypothetical protein NMB1468 as a novellipoprotein ubiquitous in Neisseria meningitidis with vaccinepotentialrdquo Proteomics vol 8 no 10 pp 2115ndash2125 2008

[284] A Pettersson J Kortekaas V E Weynants et al ldquoVaccinepotential of the Neisseria meningitidis lactoferrin-binding pro-teins LbpA and LbpBrdquo Vaccine vol 24 no 17 pp 3545ndash35572006

[285] M-C Hung J E Heckels and M Christodoulides ldquoTheadhesin complex protein (ACP) of Neisseria meningitidis is anew adhesin with vaccine potentialrdquomBio vol 4 no 2 2013

[286] D Martin B R Brodeur J Hamel et al ldquoCandidate NeisseriameningitidisNspA vaccinerdquo Journal of Biotechnology vol 83 no1-2 pp 27ndash31 2000

[287] S Ying J He M Yu et al ldquoRecombinant Neisseria surfaceprotein A is a potential vaccine candidate against Neisseriameningitides serogroup BrdquoMolecular Medicine Reports vol 10no 3 pp 1619ndash1625 2014

[288] F Haghi S N Peerayeh S D Siadat and H ZeighamildquoRecombinant outer membrane secretin PilQ

406minusminus770as a vac-

cine candidate for serogroup B Neisseria meningitidisrdquo Vaccinevol 30 no 9 pp 1710ndash1714 2012

[289] S K Gupta S Smita A N Sarangi M Srivastava B AAkhoon and Q Rahman ldquoIn silico CD4+ T-cell epitope pre-diction andHLA distribution analysis for the potential proteinsof Neisseria meningitidis Serogroup BmdashA clue for vaccinedevelopmentrdquo Vaccine vol 28 no 43 pp 7092ndash7097 2010

[290] T Fiebig F Berti F Freiberger et al ldquoFunctional expression ofthe capsule polymerase of Neisseria meningitidis serogroup Xa new perspective for vaccine developmentrdquo Glycobiology vol24 no 2 pp 150ndash158 2014

[291] J Holst P Oster R Arnold et al ldquoVaccines against meningo-coccal serogroup B disease containing outer membrane vesicles(OMV) lessons from past programs and implications for thefuturerdquo Human Vaccines and Immunotherapeutics vol 9 no 6pp 1241ndash1253 2013

[292] J Newcombe T A Mendum C-P Ren and J McFaddenldquoIdentification of the immunoproteome of the meningococcusby cell surface immunoprecipitation andMSrdquoMicrobiology vol160 no 2 pp 429ndash438 2014

[293] E Altindis R Cozzi B Di Palo et al ldquoProtectome analysis anew selective bioinformatics tool for bacterial vaccine candidatediscoveryrdquo Molecular amp Cellular Proteomics vol 14 no 2 pp418ndash429 2015

[294] M Christodoulides ldquoNeisseria proteomics for antigen discov-ery and vaccine developmentrdquo Expert Review of Proteomics vol11 no 5 pp 573ndash591 2014

[295] N E Rosenstein B A Perkins D S Stephens et al ldquoThechanging epidemiology of meningococcal disease in the UnitedStates 1992ndash1996rdquo The Journal of Infectious Diseases vol 180no 6 pp 1894ndash1901 1999

[296] E Miller D Salisbury and M Ramsay ldquoPlanning registrationand implementation of an immunisation campaign againstmeningococcal serogroup C disease in the UK a success storyrdquoVaccine vol 20 supplement 1 pp S58ndashS67 2001


[297] R Gasparini and D Panatto ldquoMeningococcal glycoconjugatevaccinesrdquo Human Vaccines vol 7 no 2 pp 170ndash182 2011

[298] F M La Force K Konde S Viviani and M-P Preziosi ldquoThemeningitis vaccine projectrdquo Vaccine vol 25 supplement 1 pp97ndash100 2007

[299] F Micoli M R Romano M Tontini et al ldquoDevelopment of aglycoconjugate vaccine to prevent meningitis in Africa causedby meningococcal serogroup Xrdquo Proceedings of the NationalAcademy of Sciences of the United States of America vol 110 no47 pp 19077ndash19082 2013

[300] R Rappuoli ldquoThe challenge of developing universal vaccinesrdquoF1000 Medicine Reports vol 3 article 16 2011

[301] C L Trotter N J Gay andW J Edmunds ldquoDynamicmodels ofmeningococcal carriage disease and the impact of serogroup Cconjugate vaccinationrdquo American Journal of Epidemiology vol162 no 1 pp 89ndash100 2005

[302] H Campbell R Borrow D Salisbury and E Miller ldquoMeningo-coccal C conjugate vaccine the experience in England andWalesrdquo Vaccine vol 27 supplement 2 pp B20ndashB29 2009

[303] R Gasparini M Comanducci D Amicizia et al ldquoMolecularand serological diversity ofNeisseria meningitidis carrier strainsisolated from Italian students aged 14 to 22 yearsrdquo Journal ofClinical Microbiology vol 52 no 6 pp 1901ndash1910 2014

[304] Public Health Agency of Canada Neisseria SPP Public HealthAgency of CanadaOttawa Canada 2011 httpwwwphac-aspcgccalab-biorespsds-ftssneisseria-engphp

Submit your manuscripts athttpwwwhindawicom

Stem CellsInternational

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014


MEDIATORSINFLAMMATION

of


Behavioural Neurology

EndocrinologyInternational Journal of



Disease Markers


BioMed Research International

OncologyJournal of



Oxidative Medicine and Cellular Longevity


PPAR Research

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Immunology ResearchHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

ObesityJournal of



Computational and Mathematical Methods in Medicine

OphthalmologyJournal of


Diabetes ResearchJournal of



Research and TreatmentAIDS


Gastroenterology Research and Practice


Parkinsonrsquos Disease

Evidence-Based Complementary and Alternative Medicine

Volume 2014Hindawi Publishing Corporationhttpwwwhindawicom


together with the peptidoglycan and inner membrane (IM)delimits the periplasm and cytoplasm compartments Manymolecules of glycolipids especially lipopolysaccharide (LPS)emerge from the outer leaflet of theOMwhile from the innerlayer of the OM lipoproteins reach the peptidoglycan withwhich they engage Moreover proteins such as porins crossthe OM these are very important for the active passive andselective permeability of small molecules ions and water [4]Most porins have a trimeric structure and an oval shape Thebacterial porins perform many functions indeed they helpthemicroorganism to adhere to the cells of the host tissue andto evade the defencemechanisms of the human body therebyfavouring invasion of the hostThey are also able to elicit bothinnate and adaptive immunity Porins can inhibit phagocyticactivity [5] and activate the complement system by meansof both classic and alternative pathways [6] For instanceNeisserial porins can activate the transport of NF-120581B intothe nucleus of B and dendritic cells (DCs) [7] The DNANF-120581B complex then recalls other proteins such as coactivatorsandRNApolymerase which transcribe theDNA intomRNAfinally this mRNA is exported to the cytosol and translatedinto proteinsThis leads to a change in the function of the cellfor example the cell may begin to produce proinflammatorycytokines

Porins are clearly involved in the induction of proin-flammatory activity although it is not known which toll-like receptors recognize them By contrast it is known thatLPS stimulates toll-like receptors 2 and 4 [8] Three distinctregions characterize LPS namely lipid A which fixes themolecule to the outer leaflet of the OM the core polysac-charide which binds to lipid A by means of a disaccharidephosphate bridge and antigen O which is the most distalportionThe general structure of LPS is fully conserved whilethe core oligosaccharide is highly variable

Toll-like receptors are a family of conserved signal trans-ducers able to induce an innate immune response To date atleast 11 mammalian TLRs have been identified Their stimu-lation by bacterial components activates the innate immuneresponse TLR2 recognizes peptidoglycan lipopeptides andbacterial proteins However it is interesting that LPS canoverstimulate the innate immune response thereby elicitinginflammation As a result the normal defences may notfunction correctly Furthermore it should be borne in mindthat TLR5 recognizes flagellin which is the main componentof bacterial flagella [9] For example mutations of the TLR4gene contribute to development of severe meningococcalinfections [10] In addition through the recognition of NmeningitidisDNA TLR9 exerts strong protection against themicroorganism [11]

22 Innate and Adaptive Immune Responses The innateimmune system is able to detect other conserved microbialcomponents called pathogen-associated molecular patterns(PAMPs) such as nucleic acid structures lipoteichoic acidand peptidoglycan [12] The pattern recognition receptors(PRRs) of immune cells include in addition to TLRs theNOD-like receptors (NLRs) and the RIG-1-like receptors(RLRs) which are able to recognize microbial componentsin the cytosol [13] TLRs NLRs and RLRs are able to activate

mitogen-activated protein kinase (MAPK) and the transcrip-tion of NF-120581B factor A different set of NLRs helps to activatecaspase-1 and the consequent assembly of inflammasomes[14]

The granulocytes and macrophages are the first cellsthat participate in the activation of the innate immuneresponse Shortly afterwards the DCs and natural killercells are activated Specifically neutrophils produce antimi-crobial proteins such as LL37 alpha and beta defensinsenzymes [15] interferons (IFN) alpha beta and gamma C-reactive protein and chemokines contribute to activating thecomplement cascade Macrophages produce reactive oxygenspecies (ROS) (eg H

2O2) and reactive nitrogen species

(RNS) Subsequently DCs which can also be activated byTLR2 and TLR4 activate natural killer (NKs) cells [16] andinduce maturation of CD4+ T cells [17ndash22]

Many bacterial components are able to stimulate theadaptive human immune response Porins can activate thetranslation of NF-120581B in the nucleus of B and DCs while classI Pilin E induces highly specific antibodies (Abs) and classII induces cross-reacting Abs Furthermore complementcascade activation as well as particularly C3b activationopsonizes antigens thereby enabling APCs to activate theadaptive response

3 Neisseria meningitidis and Immunity

31 Meningococcal Genome Meningococci have developedseveral ldquoimmunoescaperdquo strategies [23] the molecular basesof which can be understood by taking into account the natureof the Neisserial genome Progress in the field of molecularbiology and the introduction of high-throughput technolo-gies (HTTs) have tremendously advanced our understandingof the complexity of the Neisserial machinery By usingsophisticated approaches such as whole-genome sequencing(WGS) and microarrays functional genomics investigationshave uncovered the mechanisms that facilitate or hinder Nmeningitidis growth colonization and invasion and havehelped to explain its extraordinary intrastrain variation andadaptation to the environment Other techniques such asgenome-wide association studies (GWAS) have shed lighton the pathogen-host interaction and the hostrsquos susceptibilityto the microbe Genomics and postgenomics have not onlyincreased our knowledge of the biology and pathogenesisof N meningitidis but proved to be extremely useful indiscovering candidate antigens and in developing effectivenew vaccines [24]

Being a naturally competent pathogen N meningitidishas a highly dynamic plastic and flexible genome with a sizerange of only more than 2000 kilobases [25] This genomediffers from other microbial genomes in that it lacks some ofthe typical two-component systems and sigma factors [26]Despite being relatively small and compact it has elaborateda variety of mechanisms that contribute to explaining its highadaptability both to host and to environment Meningococ-cus is usually polyploid containing up to 2ndash5 genomesmdashpolyploidy being a sign of virulencemdashwhile N lactamicais monoploid [27] Neisserial pathogenicity is intrinsicallypolygenic [28] and is given by a variety of different pathogenic


















[31 75 76]



[30 79ndash87]



[88]


[25 27 3089]



[67 69 71ndash74 90 91]



[94]



[25 30 89]

Phase variation


[50 52 59]












[90 100ndash102]



[104ndash108]





[112 113]






[99 117 118]

















Table 2 Continued





[122 142143]


[90 102 122144]


[135 138145]


[90 122146]



[60]




[122 150]







[122 158159]



[39 160ndash165]

nalP


[24 102166]


nhhA


[168 169]


Table 2 Continued



norB


[100 119120 170 172]




Opa


[179ndash184]


[179ndash182 184]





Pili


[189]






[122 139173]

porB


[122 173]



[64]



Table 2 Continued










[122 195]

















2O2












































5 Conclusions







polysaccharides


ACYW-135




Bexsero(4CMenB)






HexaMen andHexaMix




12ndash18mo


P15-1 2-2)




protein carrier

MenAfriVac(MenA-TT)




MenBvac


Norway andNovartis












polysaccharides



tetanus toxoid




dose at 12mo+


15120583g CRM197



CRM197


Table 3 Continued




tetanus toxoid

Menjugate(MenC-CRM)


dose at 12mo+


to 25 120583g CRM197





No conjugation


polysaccharides






to CRM197

MeNZB


Chiron Novartis




12mo+


tetanus toxoid





MedicalCorporation








Abbreviations





adhesion molecules























Acknowledgments


References



















































































































4MD2rdquo























































































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of

































[31 75 76]



[30 79ndash87]



[88]


[25 27 3089]



[67 69 71ndash74 90 91]



[94]



[25 30 89]

Phase variation


[50 52 59]












[90 100ndash102]



[104ndash108]





[112 113]






[99 117 118]

















Table 2 Continued





[122 142143]


[90 102 122144]


[135 138145]


[90 122146]



[60]




[122 150]







[122 158159]



[39 160ndash165]

nalP


[24 102166]


nhhA


[168 169]


Table 2 Continued



norB


[100 119120 170 172]




Opa


[179ndash184]


[179ndash182 184]





Pili


[189]






[122 139173]

porB


[122 173]



[64]



Table 2 Continued










[122 195]

















2O2












































5 Conclusions







polysaccharides


ACYW-135




Bexsero(4CMenB)






HexaMen andHexaMix




12ndash18mo


P15-1 2-2)




protein carrier

MenAfriVac(MenA-TT)




MenBvac


Norway andNovartis












polysaccharides



tetanus toxoid




dose at 12mo+


15120583g CRM197



CRM197


Table 3 Continued




tetanus toxoid

Menjugate(MenC-CRM)


dose at 12mo+


to 25 120583g CRM197





No conjugation


polysaccharides






to CRM197

MeNZB


Chiron Novartis




12mo+


tetanus toxoid





MedicalCorporation








Abbreviations





adhesion molecules























Acknowledgments


References



















































































































4MD2rdquo























































































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of




















[90 100ndash102]



[104ndash108]





[112 113]






[99 117 118]

















Table 2 Continued





[122 142143]


[90 102 122144]


[135 138145]


[90 122146]



[60]




[122 150]







[122 158159]



[39 160ndash165]

nalP


[24 102166]


nhhA


[168 169]


Table 2 Continued



norB


[100 119120 170 172]




Opa


[179ndash184]


[179ndash182 184]





Pili


[189]






[122 139173]

porB


[122 173]



[64]



Table 2 Continued










[122 195]

















2O2












































5 Conclusions







polysaccharides


ACYW-135




Bexsero(4CMenB)






HexaMen andHexaMix




12ndash18mo


P15-1 2-2)




protein carrier

MenAfriVac(MenA-TT)




MenBvac


Norway andNovartis












polysaccharides



tetanus toxoid




dose at 12mo+


15120583g CRM197



CRM197


Table 3 Continued




tetanus toxoid

Menjugate(MenC-CRM)


dose at 12mo+


to 25 120583g CRM197





No conjugation


polysaccharides






to CRM197

MeNZB


Chiron Novartis




12mo+


tetanus toxoid





MedicalCorporation








Abbreviations





adhesion molecules























Acknowledgments


References



















































































































4MD2rdquo























































































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of

















Table 2 Continued





[122 142143]


[90 102 122144]


[135 138145]


[90 122146]



[60]




[122 150]







[122 158159]



[39 160ndash165]

nalP


[24 102166]


nhhA


[168 169]


Table 2 Continued



norB


[100 119120 170 172]




Opa


[179ndash184]


[179ndash182 184]





Pili


[189]






[122 139173]

porB


[122 173]



[64]



Table 2 Continued










[122 195]

















2O2












































5 Conclusions







polysaccharides


ACYW-135




Bexsero(4CMenB)






HexaMen andHexaMix




12ndash18mo


P15-1 2-2)




protein carrier

MenAfriVac(MenA-TT)




MenBvac


Norway andNovartis












polysaccharides



tetanus toxoid




dose at 12mo+


15120583g CRM197



CRM197


Table 3 Continued




tetanus toxoid

Menjugate(MenC-CRM)


dose at 12mo+


to 25 120583g CRM197





No conjugation


polysaccharides






to CRM197

MeNZB


Chiron Novartis




12mo+


tetanus toxoid





MedicalCorporation








Abbreviations





adhesion molecules























Acknowledgments


References



















































































































4MD2rdquo























































































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of

















Table 2 Continued



norB


[100 119120 170 172]




Opa


[179ndash184]


[179ndash182 184]





Pili


[189]






[122 139173]

porB


[122 173]



[64]



Table 2 Continued










[122 195]

















2O2












































5 Conclusions







polysaccharides


ACYW-135




Bexsero(4CMenB)






HexaMen andHexaMix




12ndash18mo


P15-1 2-2)




protein carrier

MenAfriVac(MenA-TT)




MenBvac


Norway andNovartis












polysaccharides



tetanus toxoid




dose at 12mo+


15120583g CRM197



CRM197


Table 3 Continued




tetanus toxoid

Menjugate(MenC-CRM)


dose at 12mo+


to 25 120583g CRM197





No conjugation


polysaccharides






to CRM197

MeNZB


Chiron Novartis




12mo+


tetanus toxoid





MedicalCorporation








Abbreviations





adhesion molecules























Acknowledgments


References



















































































































4MD2rdquo























































































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of

















Table 2 Continued










[122 195]

















2O2












































5 Conclusions







polysaccharides


ACYW-135




Bexsero(4CMenB)






HexaMen andHexaMix




12ndash18mo


P15-1 2-2)




protein carrier

MenAfriVac(MenA-TT)




MenBvac


Norway andNovartis












polysaccharides



tetanus toxoid




dose at 12mo+


15120583g CRM197



CRM197


Table 3 Continued




tetanus toxoid

Menjugate(MenC-CRM)


dose at 12mo+


to 25 120583g CRM197





No conjugation


polysaccharides






to CRM197

MeNZB


Chiron Novartis




12mo+


tetanus toxoid





MedicalCorporation








Abbreviations





adhesion molecules























Acknowledgments


References



















































































































4MD2rdquo























































































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of

























2O2












































5 Conclusions







polysaccharides


ACYW-135




Bexsero(4CMenB)






HexaMen andHexaMix




12ndash18mo


P15-1 2-2)




protein carrier

MenAfriVac(MenA-TT)




MenBvac


Norway andNovartis












polysaccharides



tetanus toxoid




dose at 12mo+


15120583g CRM197



CRM197


Table 3 Continued




tetanus toxoid

Menjugate(MenC-CRM)


dose at 12mo+


to 25 120583g CRM197





No conjugation


polysaccharides






to CRM197

MeNZB


Chiron Novartis




12mo+


tetanus toxoid





MedicalCorporation








Abbreviations





adhesion molecules























Acknowledgments


References



















































































































4MD2rdquo























































































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of






















































5 Conclusions







polysaccharides


ACYW-135




Bexsero(4CMenB)






HexaMen andHexaMix




12ndash18mo


P15-1 2-2)




protein carrier

MenAfriVac(MenA-TT)




MenBvac


Norway andNovartis












polysaccharides



tetanus toxoid




dose at 12mo+


15120583g CRM197



CRM197


Table 3 Continued




tetanus toxoid

Menjugate(MenC-CRM)


dose at 12mo+


to 25 120583g CRM197





No conjugation


polysaccharides






to CRM197

MeNZB


Chiron Novartis




12mo+


tetanus toxoid





MedicalCorporation








Abbreviations





adhesion molecules























Acknowledgments


References



















































































































4MD2rdquo























































































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of




















polysaccharides


ACYW-135




Bexsero(4CMenB)






HexaMen andHexaMix




12ndash18mo


P15-1 2-2)




protein carrier

MenAfriVac(MenA-TT)




MenBvac


Norway andNovartis












polysaccharides



tetanus toxoid




dose at 12mo+


15120583g CRM197



CRM197


Table 3 Continued




tetanus toxoid

Menjugate(MenC-CRM)


dose at 12mo+


to 25 120583g CRM197





No conjugation


polysaccharides






to CRM197

MeNZB


Chiron Novartis




12mo+


tetanus toxoid





MedicalCorporation








Abbreviations





adhesion molecules























Acknowledgments


References



















































































































4MD2rdquo























































































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of

















Table 3 Continued




tetanus toxoid

Menjugate(MenC-CRM)


dose at 12mo+


to 25 120583g CRM197





No conjugation


polysaccharides






to CRM197

MeNZB


Chiron Novartis




12mo+


tetanus toxoid





MedicalCorporation








Abbreviations





adhesion molecules























Acknowledgments


References



















































































































4MD2rdquo























































































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of






































Acknowledgments


References



















































































































4MD2rdquo























































































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of












































































































4MD2rdquo























































































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of


































































































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of
















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