Wolbachia pipientis is the only species of the genus Wolbachia, family Anaplasmataceae, order Rickettsiales, class a-proteobacteria. The genus Wolbachia is currently defined as monophyletic. W. pipientis are obligate intracellular bacteria that live in the vacuoles of eukaryotic cells. Wolbachia are coccoid or bacilliform in structure and range in size from 0.8 to 1.5 micrometers in length. Wolbachia are gram negative bacteria. They also have two cell membranes and are enclosed within a vacuole.
Wolbachia form intracellular inherited infections in many invertebrates. They are extremely common and it has been found that 20-75% of all insects are infected with the bacteria. Wolbachia can also infect numerous other non-insect invertebrates including nematodes, mites and spiders. One of the main reasons Wolbachia is so successful is the diverse phenotypes that result from infection. Wolbachia can cause quite a large number of effects on their host from classical mutualism to reproductive parasitism as characterized by the ability of Wolbachia to override chromosomal sex determination, induce parthenogenesis, selectively kill males, influence sperm competition and generate cytoplasmic incompatibility in early embryos. Though Wolbachia causes many infections most often they are benign.
Wolbachia were first described as intracellular Rickettsia-like organisms (RLOs), infecting the gonad cells of the mosquito, Culex pipien. This is how Wolbachia pipientis got its name. It was originally thought that Wolbachia only infected this common house mosquito. It however was found to infect other organisms and as of recent studies over 450 different Wolbachia strains with unique gene sequences, different phenotypes, and infecting different hosts have been identified. This large host diversity makes Wolbachia one of the most ubiquitous intracellular symbionts known to man.
Within the host cell, Wolbachia is always seen within a vacuole. This vacuole is thought to be of host origin. What exactly this compartment does and is used for is not yet known. Wolbachia are inherited vertically by transovarial transmission through the cytoplasm of host eggs. Wolbachia always infect the female germ line of its host. Wolbachia is usually lost from the cytoplasm of sperm cells during spermatogenesis which causes it to only be inherited through the female. In addition to the germ line, a range of other somatic tissues is known to be infected. Wolbachia's life cycle depends on the cytoplasmic environment of the host. The bacteria can’t be cultivated on cell-free media and can only be maintained in individual hosts or cell lines. It is thought that Wolbachia could have many applied uses for the environment such as pest and insect control and diseases associated with these pests.
References:
http://www.wolbachia.sols.uq.edu.au/
*Disclaimer - This report was written by a student participaring in a microbiology course at the Missouri University of Science and Technology. The accuracy of the contents of this report is not guaranteed and it is recommended that you seek additional sources of information to verify the contents.
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