treatment of filarial disease - umass amherst · treatment of filarial disease ... related to...
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Treatment of Filarial Disease
Still putting the pieces together
1st sequenced genome of a parasitic nematode
Brugia malayi 95 megabase - ~19,000 genes Project initiated in 1994 (WHO)
Representative nematode Availability of material from all life
cycles stages Goals
Construction of genomic libraries - mapping of genome
Identify novel genes (different life cycle stages)
Implement globally accessible database and resources
Dissemination of filiarial genome data and materials
NIAID/TIGR 2001 - turning point
Steve Williams Mark Blaxter
Univ. of Edinburgh Sanger Center
Smith College TIGR
New England Biolabs
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The Filariasis Repository Service was first funded by the NIAID/NIH in 1968. The Repository has served as a unique supply source of filarial research
materials and technical information for investigators unable to cyclically maintain parasites due to expense, lack of expertise lack of space backup facility for investigators who experienced difficulties with their own
colonies. Molecular and Biological Resources
Long term storage - cryopreservation Distributed freely - only have to pay for shipping cost
Those in endemic countries do not even pay for shipping!
Brugia malayi Annotation Jamboree May 2005: TIGR, Rockville, MD, USA
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Intriguing Observations!
1975 - W.J. Kozek (Electron microscopist) High resolution imaging revealed intracellular bacteria in filarial worms but not
in other nematodes (non-quantitative - observational)
Clinicians believed that antibiotics were effective against acute symptoms of filariasis (India) - treated patients
Klei and McCall independently found that a broad-spectrum antibiotic resulted in the failure of parasites to grow in infected animals.
Wolbachia (B. malayi) genome project Filarial Genome Project
Williams/Blaxter found many sequences resembling bacterial rDNA - contaminants?
Rediscovery of Kozek, Keil and McCall data
Completed March, 2004
Comparative genome analysis with other endosymbionts March, 2005
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Wolbachia Gram-negative bacterial endosymbiont form intracellular inherited infections in many
invertebrates. In reproductive tissues Infects arthropods (insects, crustaceans, spiders and
mites) and nematodes - approx 20% of insects species are infected
Does not infect vertebrates (mammals and humans)! Host range of Wolbachia is not fully appreciated Parasitism or mutualism?
Host gives bacteria nutrients and protection Bacteria gives host? Manipulates sex life of host
Wolbachia
Related to Rickettsia bacteria Alpha-proteobacterium
Much of the success of Wolbachia can be attributed to the diverse phenotypes that result from infection:
Wolbachia can override chromosomal sex determination induce parthenogenesis (typically all female) selectively kill males influence sperm competition generate cytoplasmic incompatibility in early embryos
Research interest ranges from the evolutionary implications of infection to the use of this agent for pest and disease control.
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Wolbachia genomes
Trends Parasitol. 2006 22:60-65 Wolbachia genomes: revealing the biology of parasitism and mutualism
Para
sitic
Mut
ualis
tic
Primarily CI
Wolbachia Wolbachia
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Unidirectional Cytoplasmic Incompatibility
Red - infected Black - uninfected Infected females produce more offspring
Distribution of Wolbachia
Microfilaria: Wolbachia are detected with
anti-WSP
Mosquito derived L3 Bacteria were rarely seen
L3: 9 days pi lateral cord localization
L3: 9 days pi Enlargement
Dividing cell
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Distribution of Wolbachia L4 - large numbers in lateral cords
Adult female - lateral cords, mf
Low Wolbachia numbers
High Wolbachia numbers
Distribution of Wolbachia
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Wolbachia association
A: Demonstration of Wolbachia in hypodermis (anti-WSP staining)
B: Staining for Wolbachia (inset) and neutrophils stained for defensin protein
C: Patient treated with doxycyline. No anti-WSP staining in worm, substantial decrease in defensin staining.
Wolbachia of filarial worms
Obligate endosymbionts! - mutualistic relationship Depletion of Wolbachia results in filaria that fail to molt to adult stage “ “ fail to mate “ “ fail to produce progeny
STERILIZING effect!
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Host response to filarial worms Interpretation of host responses
Crude extract of filarial antigens - what did these contain? Mimicked Host response to acute infections/ adult killing
Wolbachia antigen preparations could account for pathology in a mouse model of Onchocerca volvulus. Combined treatment with anti-filarial and tetracycline
Clearing of microfilaria - decrease in total number Pretreatment with tetracycline
Decreased number of wolbachia, as well as the # and severity of adverse reactions
Filarial Disease Control New tool for eradication?
Deplete endosymbiont Worms develop distinct
phenotype Decrease # of microfilaria Embryogenesis is blocked Uteri of adult females contain
degenerated embryos Some studies induced killing of
adults
New measure for control?
+ Mass drug treatment