The Minus Sense and Ambisense RNA Viruses

There are 7 families of minus strand RNA viruses

All minus strand RNA viruses are enveloped with helical nucleocapsids. Families may differ in morphology of the virion, however.

No polyproteins are made and the viruses do not encode proteases.

Because the viral genomes are not mRNAs, all must contain enzymes within the virion to synthesize mRNA.

Four families have a single piece of RNA as their genome and are grouped into the order Mononegavirales. The remaining three familes have segmented genomes.

Minus strand or ambisense viruses infect vertebrates or plants. Some are arboviruses and thus infect arthropods as well.

All RNA synthesis takes place within nucleocapsids. The genome is never released free into the cytoplasm.

NEGATIVE STRAND RNA VIRUSES

Orthomyxoviridae

Bunyaviridae

FAMILY/ GENUS

HOST(S) TRANSMISSION

MONONEGAVIRALES (NONSEGMENTED NEGATIVE STRAND VIRUSES)Rhabdoviridae

Filoviridae

Paramyxoviridae

SEGMENTED NEGATIVE STRAND RNA VIRUSES

Two genera of plant viruses

GENOME SIZE TYPE VIRUS

Vertebrates Some arthropod-borneVesiculovirus VSIVLyssavirus Contact with salivaVertebrates RabiesEphemerovirus Arthropod-borneCattleBEFVNovirhabdovirus FishIHNV

13-16

13

16-20

Vertebrates “Marburg-like viruses” Marburg

13 in 8 segments

Respirovirus Sendai AirborneVertebrates

11-20 in 3 segments

ArenaviridaeVertebrates

10-14 in 2 segmentsArenavirus LCMV

Morbillivirus Measles AirborneVertebratesRubulavirus Mumps AirborneVertebrates

AirborneMegamyxovirus Hendra VertebratesPneumovirus HRSV AirborneVertebrates

Vertebrates Bunyavirus Bunyamwera Mosquito-borneHantavirus Hantaan Vertebrates Feces/urine/salivaNairovirus Dugbe Vertebrates Tickborne

Arthopod-bornePhlebovirus Rift Valley fever Vertebrates Tospovirus TSWV Plants Thrips

Urine/saliva

Metapneumovirus TRTV Turkeys Airborne

Influenzavirus C AirborneInfluenza C Vertebrates

Bornaviridae ~9 BDV Vertebrates Bornavirus

“Ebola-like viruses” Zaire Ebola virus Vertebrates

Vertebrates Influenzavirus A Airborne Influenza A Influenzavirus B Influenza B Vertebrates Airborne

Arthropod-borne

Thogotovirus Thogoto Vertebrates Arthropod-borne

( in kb)

3' 5'

RUBULAVIRUS

MONONEGAVIRALES

PB1RNA5 RNA8 RNA7

ORTHOMYXOVIRIDAE

N NS1/NS2 M1/M2 NAHA

PB2 PA

Nucleocapsid Genes Glycoprotein Gene(s) Polymerase Gene(s)

SEGMENTED

BUNYAVIRIDAE

N G2 NSm

S RNA M RNA L RNA

L BUNYAVIRUS

ARENAVIRIDAE S RNA L RNA

L ARENAVIRUSN G2 G1

RNA4 RNA 1 RNA 3RNA2RNA6

(SSHV)

(LCMV)NS

(FLUAV)

BORNAVIRIDAE

le N P M G L BORNAVIRUS(BDV)

tr

FILOVIRIDAE

le FILOVIRUS(ZEBOV)

N P M1 GP LM2p30tr

le N P M G

RHABDOVIRIDAEVESICULOVIRUS

(VSIV)L tr

PARAMYXOVIRIDAE

P/V F HN(SV-5)

MN LSHle tr

NSs

NSs

G1

INFLUENZAVIRUS A

RHABDOVIRIDAE

VESICULOVIRUS

LYSSAVIRUSRabies

EPHEMEROVIRUS

Worldwide, except Australia, PNG, and Antarctica

Africa, Asia, Australia,

CYTORHABDOVIRUS

Humans, dogs, skunks, foxes, raccoons

Adelaide River virus

Berrimah virus

Lettuce necrotic yellows Northern cereal mosaicStrawberry crinkle

NUCLEORHABDOVIRUS

AphidsLeafhopperAphid

Potato yellow dwarf LeafhopperMaize mosaic Leafhopper

Sonchus yellow net Aphid

Cattle, water buffalo

Hematophagous arthropods

Infectious saliva

Fever, anorexia

Malaise, then delirium, then coma and death

PlantsPlantsPlants

Plants

Plants

Plants

Bovine ephemeral fever

Europe, Africa, Australia

Bat lyssaviruses Bats, humans

Like rabies

Vesicular stomatitis Indiana

AmericasHumans, horses, ruminants, swine

Vesicles on tongue and lips

Airborne,Insects?

Mokola AfricaHumans, dogs, cats, shrews

Like rabies?

GENUS/ MEMBERS

USUAL HOST(S)

TRANSMISSION/ VECTOR?

DISEASE WORLD DISTRIBUTION

Piry Mice, humans

BrazilFebrile illnessSandflies

India, Asia?Chandipura Sandflies Febrile illnessMammals including humans

Infectious saliva

NOVIRHABDOVIRUSSalmonid fish Pacific Northwest

of N. A.HemorrhageInfectious

hematopoietic necrosis (and other fish viruses)

?

Vesicular Stomatitis Virus

Nucleocapsids

of

(-)RNA

Viruses

Schematic Diagram of a Rhabdovirus

G

M

NS

N

RNA

L

Lipid Bilayer

le N P M G L tr

SIE3’ 5’

Genome RNA

G mRNAM mRNA

...AUAGGGAUACUUUUUUUGAUUGUCUCUAG...5’ 3’Gppp

m

AACAGAGAUC......UAUCCCUAUG poly(A)

A. Location of intergenic sequences of VSV (a rhabdovirus), and detailed view of the M/G intergenic region

B. Genomic sequences at other intergenic regions in the VSV genome3’ 5’

N/P ...CGAUGUAUACUUUUUUUGAUUGUCUAUAG...P/M ...CAUCUGAUACUUUUUUUCAUUGUCUAUAG...G/L ...UUAAAAAUACUUUUUUUGAUUGUCGUUAG...

mRNAS

Diagram of the VSV Genome and the Structure of the Gene Junctions

Replication of Rhabdovirus RNA

Switch from mRNA synthesis to RNA replication occurs when sufficient N protein has been made to encapsidate the newly synthesized RNA.

The (+)RNA is then encapsidated during synthesis and a perfect complementary copy of the genome is produced. Stop signals, poly(A) signals, reinitiation signals are all ignored.

The encapsidated antigenomic RNA can be used in turn to synthesize more genomic RNA

Synthesis of genomic (-)RNA also requires encapsidation of the newly synthesized RNA during synthesis.

Thus, protein synthesis is required for replication of the genome but not for synthesis of mRNAs.

Genomic RNA and antigenomic templates are never free but are always present in nucleocapsids, whereas mRNAs are not encapsidated.

Budding VSV

Rabies VirusThe most dangereous rhabdovirus is rabies virus and its ally bat lyssavirus

The virus is associated with wildlife--it is a zoonotic virusThe virus is usually transmitted to humans by the bite of a rabid animal--

there is no human-to-human transmission

The virus first replicates around the site of the bite

The probability of CNS infection depends upon the location of the bite

Once the symptoms of rabies occur the infection is uniformly fatal

Louis Pasteur developed an early vaccine against rabies

50,000 humans die each year of rabies

A modern vaccine is widely used to prevent rabies

One million people are inoculated each year following exposure

Because transfer to the brain in delayed, the vaccine can be administered postexposure

Transmission to the CNS may occur upon infection of axons near the site

Bats are an important reservoir. Transmission to humans from bats may sometimes occur through aerosols.

2000199019801970196019501940

10

20

30

40

50

60

Year

10,000

8000

6000

4000

2000DEATHSCASES

Human Rabies

Dogs

Wildlife

Nu

mb

er o

f H

um

an D

eath

s (c

ases

) p

er Y

ear

Nu

mb

er o

f A

nim

al C

ases

per

Yea

r

Rabies in the United States, 1940-1995

Ohio

North Carolina

Virginia

Pennsylvania

New York

Maine

New Hampshire

Massachusetts

Rhode Island

New Jersey

Connecticut

DelawareMaryland

Vermont

1977-1979

1980-1984

1985-1989

1990-1994

1994-1998

No raccoon rabies detected

West Virginia

Spread of Raccoon Rabies throughout the Atlantic Seaboard

Control of Rabies by Vaccination of Wildlife

Wildlife in areas of the U.S. and Europe have been vaccinated using baits containing vaccine.

The bait contains attenuated rabies virus or contains vaccinia virus that expresses rabies G protein.

The bait is often broadcast from planes.

Such programs have been moderately successful in containing the spread of rabies, but are expensive and manpower-intensive.

ParamyxovirusesParamyxoviruses have genomes of 15-20 kb and have 8-11 (or more) genes

Six genera are currently recognized

The family contains many important human pathogens

Many viruses cause respiratory disease including pneumonia

Mumps virus and measles virus are paramyxoviruses

Transmission of the viruses is by aerosols

To date, only mammals and birds are known to be infected by paramyxoviruses

Two recently identified viruses cause encephalitis in humans

Many are specific for a particular host

Many of the human viruses infect only humans

Virions are usually spherical when grown in culture, but clinical specimens are often filamentous

PARAMYXOVIRIDAE

RESPIROVIRUSHuman parainfluenza 1,3

Airborne WorldwideHumans Respiratory disease

Sendai Mice Worldwide

Worldwide

Paramyxovirinae

Bovine parainfluenza 3

MORBILLIVIRUSMeasles

Distemper Dogs, marine mammals

Worldwide

Rinderpest

Humans, monkeys

PneumovirinaePNEUMOVIRUSHuman respiratory syncytial

Humans

Bovine respiratory syncytial

Cattle

Pneumonia virus of mice

Mice

Turkeys

RUBULAVIRUSMumps Humans

Human parainfluenza 2, 4a, 4bSimian virus 5

Parotitis, orchitis, meningitis

Worldwide

Fever, rash, SSPE, immune suppression

Cattle, swine Gastroenteritis

Immune suppression, gastroenteritis, CNS disease

Worldwide

Monkeys, canines

Cattle, sheep

Respiratory distress, diarrhea

Gallinaceous birds

Worldwide

Newcastle disease ,

Worldwide

Worldwide

Worldwide

Worldwide

Worldwide

Worldwide

Worldwide

METAPNEUMOVIRUS

MEGAMYXOVIRUS Hendra (equine morbillivirus)

Humans, equines, Pteropus fruit bats

AustraliaRespiratory disease, encephalitis

Body fluids?

Nipah Humans, swine, cats, dogs

Malaysia, Singapore

GENUS/ MEMBERS

USUAL HOST(S)

TRANSMISSION DISEASE WORLD DISTRIBUTION

Airborne

Airborne

Airborne

Airborne

Airborne

Airborne

Airborne

Airborne

Airborne

Humans

Turkey rhinotracheitis

Respiratory disease, encephalitis

Body fluids?

Airborne

Airborne

Airborne

Airborne

Respiratory diseaseRespiratory disease

Respiratory diseaseRespiratory disease

Respiratory diseaseRespiratory diseaseRespiratory disease

Respiratory disease

SV5

Negative strain Sectioned

Measles virus

SV5

Budding Filamentous Form of SV5

Figure 4.6

genome (kb)

161086420 18

Genome Organizations of Five Genera of theParamyxoviridae.

RESPIROVIRUSHPIV-315462 nt2258572539353603515

LHNFMP/CNaa

RUBULAVIRUSSV-5

15246 nt510 392 529377

SH

44 565 2255N V/P M F HN L

aa

MORBILLIVIRUSMeV

15894 ntL

2183 N 525

P507

M335 553

F H617aa

MEGAMYXOVIRUS (Hendra virus, 18234nt)

N532

P/V/C707 546

FM352

G604

L2244 aa

PNEUMOVIRUS HRSV

15225ntNS1NS2

139124

N391

P241

M256 65

G299 574

F M2195/90

L2166

SH

aa

3’ 5’

MEASLESMORBILLIVIRUS

HPIV-2, HPIV-4, SV-5, (NDV)

SENDAI

HPIV- 3

MUMPS

HPIV- 1 C protein

P protein

C proteinP protein

V protein+ 1 G

RESPIROVIRUS

RUBULAVIRUS

ORF1 ORF2 ORF3 Cysteine-rich domain

C proteinP protein

V protein+ 1 G

* **** *

V protein

+ 4G I protein

+ 2G P protein

* **** *

V protein+ 2G

P protein

* **** *

C proteinP protein

D protein+ 2G

V protein+ 1 G

* **** *

* **** *

MEGAMYXOVIRUSNIPAH

* **** *

P proteinC protein

V protein+ 1 G

****

Translation Strategy of the P Gene of Paramyxoviruses

Pneumovirinae

Paramyxovirinae

Subfamily

Pneumovirus Metapneumovirus

Genus Species 100 nt substitutions

NDV HPIV-2

SV-5 MuV

HPIV-4a HPIV-4b

HPIV-1 SeV

HPIV-3 CDV PDV

RPV MeV

PPRV DMV

TRTV HRSV

Respirovirus

Morbillivirus

Megamyxovirus Hendra Nipah

Rubulavirus

Phylogenetic Tree of the Paramyxoviridae (Derived from the sequences of the N ORF)

Measles virus

Measles virus was once epidemic throughout the world. Very few people escaped infection by it.

It is spread by aerosols and begins infection in the URT. It then becomes systemic and infects many organs.

It causes a serious illness. It leads to temporary suppression of the immune system and infected persons may succumb to secondary infectionn.Infection of the CNS can lead to neurological sequella, including SSPE.

A live vaccine, part of the MMR vaccine, has almost eradicated measles from the Americas. The virus is still epidemic in Africa and parts of Asia, however, and imported cases have resulted in small epidemics in the U.S.

Worldwide 2.5 million/year died from measles.

Measles Virus History

Measles virus is a human virus and humans are the only reservoir in nature.

Infection results in solid, life-long immunity.

Spread is by direct person-to-person contact.

Therefore a minimum population size of about 500,000 is required to maintain the virus, and measles could not have existed before human populations reached this size.

This may have occurred about 5000 years ago following domestication of plants and animals.

When the virus was first introduced into naïve populations during European exploration 200-500 years ago, the death toll was enormous. One result, aided by smallpox, was the depopulation of the Americas.

20

15

10

5

01 2 3 4 5 6 70

Iceland

New HebridesNew CaledoniaSolomon Islands

French Polynesia

Tonga

Western Samoa

Mean Distance Between New Susceptibles (Kilometers)

Du

rati

on

of

Ep

idem

ics

of

Measl

es

(Mon

ths)

B.

100

80

60

40

20

04 8 12 16

Guam

Bermuda

A.

New Susceptibles in Thousands per Year

Perc

en

t of

Mon

ths

wit

h C

ase

s of

Measl

es

Effect of Population Size and Density on the Epidemiology of Measles

Measles vaccine licensed

1982 1987 1992 1997Rep

orte

d C

ases

(th

ousa

nd

s)

Rep

orte

d C

ases

(th

ousa

nd

s)

30

20

10

0

1962 1967 1972 1977 1982 1987 1992 1997

500

450

400

350

300

250

200

150

100

50

0

Cases of Measles in the United States, 1962 to 1997

5 10 15 20 25 30 35 40Age (Months)

EZ-HT

SW-HT

Standard

Mort

ali

ty (

per

10

00

ch

ild

ren

at

5 m

on

ths)

200

150

100

50

0

Trial in Senegal with High-Titer Measles Vaccine

Rep

ort

ed

case

s /1

00

,00

0 p

op

ula

tion

Mumps vaccine licensed in 1967

1968 1972 1976 1980 1984 1988 1992 1996

1982 1987 1992 1997

76

54

32

10

Rep

ort

ed

case

s /1

00

,00

0 p

op

ula

tion 90

80

70

60

50

40

30

20

10

0

Incidence of Mumps in the United States, 1968-1998

Respiratory Syncytial Virus

RSV is the leading cause of pneumonia in infants worldwide.

Infection begins in the URT but spreads to the LRT in ~1/3 of primary infections.

Immunity following infection is incomplete and children and adults suffer recurrent infections.

Disease symptoms are usually milder in second and subsequent infections, however.

RSV infection of immunocompromised persons is very serious.

No vaccine exists. Clinical trials with an inactivated virus vaccine gave the disastrous result that vaccinated individuals suffered more serious illness upon subsequent infection by RSV.

VIRUSES CAUSING RESPIRATORY DISEASE

Family Virus Nucleic Acid Host Range

RSV = respiratory syncytial virus; NDV = Newcastle disease virus; HCoV = human coronavirus; IBV = infectious bronchitis virus; CLTV = canine laryngotracheitis; EBV = Epstein-Barr virus.

Adapted from Tables of Respiratory Viruses pp 1493,1494 in the Encyclopedia of Virology.

Disease(s)

Picornaviridae ss plus strand RNA

HumansRhinoviruses Common cold (rhinitis), pharyngitis

Coxsackie A Humans Rhinitis, pharyngitis

Coronaviridae ss plus strand RNA

HCoV Humans RhinitisIBV Fowl Bronchitis

OrthomyxoviridaeInfluenza ss minus strand RNA

Humans, birds, horses, swine

Rhinitis, pharyngitis, croup, bronchitis, pneumonia

Paramyxoviridae RSV ss minus strand RNA

Humans, cattle Rhinitis, pharyngitis, croup, bronchitis, pneumonia

Human parainfluenza

Humans Rhinitis, pharyngitis, croup, bronchitis, pneumonia

Measles Humans Pneumonia

Canine distemper Dog Bronchitis, pneumoniaBirdsNDV Respiratory distress

Caliciviridae Feline calicivirusss plus strand RNA

Cats Rhinitis, tracheitis, pneumonia

Herpesviridae Cytomegalovirus Humans Pharyngitis, pneumoniads DNAHerpes simplex, EBV, varicella

Humans Pharyngitis, pneumonia

Various alphaherpesvirinae

Cattle, cat, horse, chicken

Rhinotracheitis

Adenoviridae Human Ad40,41 ds DNA Humans Rhinitis, pharyngitis, pneumoniaCLTV Dog Pharyngitis, tracheitis, bronchitis,

and bronchopneumonia

Hendra Virus and Nipah Virus

Hendra virus first appeared in Australia in 1994

Associated with an outbreak of equine respiratory disease

Three humans became ill from the virus, two of whom died.

Nipah virus first appeared in 1998 in Malaysia and Singapore.

Causative agent of an epidemic of human encephalitis

258 cases occurred with 40% mortality rate

Associated with pigs, which served as amplifying hosts

These two viruses are related and flying foxes are now known to be the reservoir

They represent emerging viruses that were previously unknown but suddenly appeared to cause serious human illness

Filoviridae

MARBURG-LIKE VIRUSESMarburg

Reston Ebola

Sudan Ebola

Zaire Ebola

Humans

Humans

Cynomolgus monkeys

Contact with bloodor other body fluids

*Natural reservoirs unknown

AfricaSevere hemorrhagicdisease

Severe hemorrhagic disease in monkeys, attenuated in man

Philippines

Contact with bloodor other body fluids

Severe hemorrhagicdisease

Africa

EBOLA-LIKE VIRUSES

Cote d’Ivoire Ebola

*GENUS/

MEMBERSUSUAL HOST(S)

TRANSMISSION DISEASE WORLD DISTRIBUTION

VIRUS NAMEABBREV.

MARV

SEBOV

ZEBOV

CIEBOV

REBOV ?

Filovirus Virions

Marburg Virus Ebola Zaire Virus

200 nm 200 nm

Filovirus Outbreaks

Marburg

Ebola

Year Cases/ %Mortality

Year Cases/ %Mortality

1975 3 (33%) Zimbabwe1980 2 (50%) Kenya1987 1 (0%) Kenya

1976 284 (53%) Sudan

1994 44 (64%) Gabon1994 1 (0%) Ivory Coast

1995/9637 (57%) Gabon1996/97 60 (75%) Gabon

1998/0099 (80%) Zaire*

*Now called Democratic Republic of Congo

*1977 1 (100%) Zaire1976 318 (88%) Zaire

*

1995 315 (77%) Zaire (Kikwit)*

Sudan

GabonKenya

Zaire*

Zimbabwe

•1980•1987

•1975

•1976•1979

Ivory Coast

•1976

•1994•1995/96•1996/97

•1995

•1994

•1998/00

•1977

1979 34 (65%) Sudan

Uganda•2000

2000 425 (53%) Uganda

Country

Country

30201000

100

200

300

400

500

Ebola Epidemic in Uganda - October 2000 through January 2001

Cu

mu

lati

ve To

tals

Cases

Deaths

October 10 20November

10 20December Jan.

Borna Disease Virus

Borna disease virus is a (-)RNA virus of 9 kb.

Originally known as a pathogen of horses and sheep, it probably infects all warm blooded vertebrates.

Where known, it infects the CNS and produces only small amounts of virus.

It is associated with abnormalities in movement and behavior.

In horses, the disease may ameliorate or may progress to paralysis and death.

Infection is not cleared by the immune system and becomes chronic.

There is preliminary evidence that the virus may be associated with neurological disease in humans, including schizophrenia and bipolar disease.

Its geographic range is probably worldwide.

Borna Disease Virus

100 nm

Borna Disease Virus Transcription Map

Borna disease virus replicates in the nucleus and many mRNA are spliced