Tens of thousands of wasp species inject caterpillars with paralyzing toxins so that they can lay their eggs inside, allowing their young to eat the innards as they grow. These toxins have been a bit of a mystery to researchers, but a new genetic analysis suggests that the toxins came from a virus that infected wasps millions of years ago.
In the 1970’s the toxins were found to resemble viruses and so were named polydnaviruses. However this classification was debated because the toxins did not seem to contain any of the proteins usually found in viruses for replication. Jean-Michel Drezen, an entomologist from France, was intent on settling the debate, and so with the help of his colleagues he proceeded to decode the first complete sequence of polydnavirus in 2004. After continued research it was found that in one group of wasps, 22 genes - that coded for important structural proteins in the wasp’s polydnavirus toxins - matched those of an ancient family of viruses called nudiviruses.
Drezen concluded from his findings that a few million years ago, nudiviruses infected wasps, and over time the viral DNA integrated into the wasp genome. It is now evident today that the wasp needs the virus to survive, and the virus needs the wasp to survive. The wasp needs the virus for its use as a toxin during its reproduction process, and the virus needs the wasp because the only place it can replicate is inside the wasp’s ovaries.
Further research into how these viruses work could have useful clinical applications because the polydnavirus acts as a gene vector capable of carrying large amounts of DNA.
Source:
http://sciencenow.sciencemag.org.ezproxy.library.uq.edu.au/cgi/content/full/2009/212/2
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