Wolbachia

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Concepts

• Endosymbioses

• Host manipulation

• Co-evolutionGoogle images

History

• One of the most infectious bacterial genera on earth

• Endosymbionts • First discovered in 1924 in insects; largely

unknown until the 1990s (Evade detection)• Now known to be in nematodes• Applications for bio-control and treatment of

nematode diseases

Diversity

Infects over 1 million species of insects and other invertebrates!

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Stevens et al, 2001

Wolbachia in insects

• Maternally inherited (Usually)

• Cytoplasmic incompatibility

• Induced parthogenesis, functional feminization, and male killing

• Protection from parasitoid wasp in pea aphids

• Evolutionary implications

Cytoplasmic Incompatibility (CI)

Cytoplasmic incompatibility

Tortora et al, 2010

Biocontrol (economic implications)

• Cytoplasmic incompatibility has enormous implications for bio-control

• Exp 1) The Med fly- experimentally inoculated males induced complete (CI) in target populations

• Populations were “suppressed” by a single release of infected males

Zabalou et al, 2004

Evolutionary Implications

Experiment 2- Antibiotic treatment in wasps

• Does Walbachia help maintain the uniqueness of it’s hosts species by impeding “hybrid” development?

• How has Wolbachia influenced the evolution of insects?

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Hybridization!

A twist: Wolbachia is found in filarial nematodes where it is discovered to be

an vital symbiont

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Co-evolution• Strong evidence for co-evolution between

endosymbiont Wolbachia and nematodes

• Phylogenetic congruency

• Long history of vertical transmission

An Obligate Endosymbiosis• Wolbachia vital for embryogenesis in adult females

• Inhibition of microfilariae

• Molt inhibition

Filariasis in Humans and animals

• 200 million individuals infected across 90 countries (krager, 2007 as cited by Hoerauf)

Canine Heart WormD. immitis

Elephantiasis /ESLFWuchereria bancrofti

River BlindessO. ochengi

Traditional Treatment (Filariasis)Traditional treatment for lymphatic

Filariasis - Ivermectin

Now- Effectively use chemotherapy to disrupt parasite/symbiont interactions in filarial nematodes

Medical Application?Experiment 3

• A doxycyline regime can be used to treat (Ghanaian) individuals for lymphatic filariasis by targeting the host symbiont

• Results: a 99% reduction in microfilaria

• Implications- doxycyline as a universal treatment for filariasis in humans

Ivermectin vs Doxycycline

$111.17 USD/ 3 mg (Merck)

Neurotoxic effects

Annual Treatment-Kills the microfilariae not the worm

$225.99 USD/100mg

Pregnancy risk factor D

6 weeks course, makes adult worms sterile

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Conclusions• Wolbachia is a fundamental bacteria genus

• Further study of this endosymbiont will enhance our understanding of evolutionary entomology, Nematode symbiont coeveolution, and other biological systems

• Targeting Wolbachia for biocontrol and disease eradication will have huge economic and medical benifits

References

Stevens, L., Giordano, R., & Fialho, R. F. (2001). MALE-KILLING, NEMATODE INFECTIONS, BACTERIOPHAGE INFECTION, AND VIRULENCE OF CYTOPLASMIC BACTERIA IN THE GENUS WOLBACHIA. Annual Review of Ecology & Systematics, 32: 519

Hoerauf, A., Mand, S., Fischer, K., Kruppa, T., Marfo-Debrekyei, Y., Debrah, A., & ... Bättner, D. W. (2003). Doxycycline as a novel strategy against bancroftian filariasis—depletion of Wolbachia endosymbionts from Wuchereria bancrofti and stop of microfilaria production. Medical Microbiology & Immunology... Study 3

Sofia Zabalou, Markus Riegler, Marianna Theodorakopoulou, Christian Stauffer, Charalambos Savakis, Kostas Bourtzis, John H. Law (2004). Wolbachia-Induced Cytoplasmic Incompatibility as a Means for Insect Pest Population Control. Proceedings of the National Academy of Sciences of the United States of America Vol. 101, No. 42 (Oct. 19, 2004), pp. 15042-15045....Study 1

Tortora, G., Funke, B., Case, C. (2010).Microbiology: An Introduction 10th Ed. 305-307...Study 2

Hoerauf, A., Rao, R. U. (2007). Wolbachia: A Bug’s Life in another Bug

Questions