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Wolbachia
Scientific classification
Kingdom: Bacteria Phylum: Proteobacteria Class: Alpha Proteobacteria Order: Rickettsiales Family: Rickettsiaceae Genus: Wolbachia

Wolbachia is a genus of inherited bacterium that infects arthropod species, including a high proportion of all insects. It is one of the world's most common parasitic microbes and is potentially the most common reproductive parasite in the biosphere, for example more than 16% of insect species in Panama carry this bacterium^{[citation needed]}.

Contents 1 Association with disease 2 See also 3 References 4 External links

Outside of Insecta, Wolbachia infects a variety of isopod species, spiders, mites, and many species of filarial nematodes (a type of parasitic worm), including those causing onchocerciasis ("River Blindness") and elephantiasis in humans as well as heart worms in dogs. Not only are these disease-causing filarial infected with Wolbachia, but Wolbachia seem to play an inordinate role in these diseases. A large part of the pathogenicity of filarial nematodes is due to host immune response toward their Wolbachia. Elimination of Wolbachia from filarial nematodes generally makes them either dead or sterile (Hoerauf et al. 2003). Consequently, current strategies for control of filarial nematode diseases include elimination of Wolbachia via the simple doxycycline antibiotic rather than far more toxic anti-nematode medications (Outland 2005, Taylor et al. 2005).

Within arthropods, Wolbachia is notable for significantly altering the reproductive capabilities of its hosts. These bacteria can infect many different types of organs, but are most notable for the infections of the testes and ovaries of their hosts.

Wolbachia are known to cause four different phenotypes:

• male killing (death of infected males)
• feminization (infected males develop as females or infertile pseudo-females)
• parthenogenesis (reproduction of infected females without males) and
• cytoplasmic incompatibility (the inability of Wolbachia-infected males to successfully reproduce with uninfected females or females infected with another Wolbachia strain).

Wolbachia are present in mature eggs, but not mature sperm. It is only infected females that pass the infection on to their offspring. It is thought that the phenotypes caused by Wolbachia, especially cytoplasmic incompatibility, have been important in promoting speciation^{[citation needed]}. It can cause misleading results in molecular cladistical anaslyses (Johnstone & Hurst 1996).

The bacteria were first identified in 1924 by Hertig and Wolbach in Culex pipiens, a species of mosquito (Hertig and Wolbach, 1924).

The genomes of Wolbachia from Drosophila melanogaster flies ^[1]and Brugia malayi nematodes ^[2]have been sequenced, and genome sequencing projects for several other Wolbachia strains are in progress.

• Intragenomic conflict

• Hertig, M. & Wolbach, S. B. (1924): Studies on Rickettsia-like microorganisms in insects. Journal of Medical Research 44: 329-374.

• Hoerauf, A.; Mand, S.; Fischer, K.; Kruppa, T.; Marfo-Debrekyei, Y.; Debrah, A. Y.; Pfarr, K. M.; Adjei, O. & Buttner, 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 and Immunology 192(4): 211-216. PMID 12684759 DOI:10.1007/s00430-002-0174-6 (HTML abstract)

• Johnstone, Rufus A. & Hurst, Gregory D. D. (1996): Maternally inherited male-killing microorganisms may confound interpretation of mitochondrial DNA variability. Biol. J. Linn. Soc. 58(4): 453–470. HTML abstract

• Outland, Katrina (2005): New Treatment for Elephantitis: Antibiotics. Journal of Young Investigators 13. HTML fulltext

• Taylor, M. J.; Makunde, W. H.; McGarry, H. F.; Turner, J. D.; Mand, S. & Hoerauf, A. (2005): Macrofilaricidal activity after doxycycline treatment of Wuchereria bancrofti: a double-blind, randomised placebo-controlled trial. Lancet 365(9477): 2116-2121. PMID 15964448 DOI:10.1016/S0140-6736(05)66591-9 (HTML abstract)

• Zimmer, Carl (2001): Wolbachia: A Tale of Sex and Survival. Science 292 (5519): 1093-1095. DOI:10.1126/science.292.5519.1093 HTML fulltext

1. ^ Wu M et al., "Phylogenomics of the reproductive parasite Wolbachia pipientis wMel: a streamlined genome overrun by mobile genetic elements.", PLoS Biol, 2004 Mar;2(3):E69
2. ^ Foster J et al., "The Wolbachia genome of Brugia malayi: endosymbiont evolution within a human pathogenic nematode." PLoS Biol. 2005 Apr;3(4):e121. Epub 2005 Mar 29.

• Virtual Museum of Bacteria: Wolbachia information site. Retrieved 2006-DEC-19.
• National Science Foundation: Wolbachia research portal. Retrieved 2006-DEC-19.