Virus carrying DNA of black widow spider toxin discovered

Date: October 11, 2016

Source: Vanderbilt University

A tiny virus that may sting like a black widow spider.

That is one of the surprise discoveries made by a pair of Vanderbilt biologists when they sequenced the genome of a virus that attacks Wolbachia, a bacterial parasite that has successfully infected not only black widow spiders but more than half of all arthropod species, which include insects, spiders and crustaceans.

"Discovering DNA related to the black widow spider toxin gene came as a total surprise because it is the first time that a phage -- a virus that infects bacteria -- has been found carrying animal-like DNA," said Associate Professor of Biological Sciences Seth Bordenstein. He and Senior Research Specialist Sarah Bordenstein reported the results of their study in a paper titled "Eukaryotic association module in phage WO genomes from Wolbachia" published Oct. 11 in the journal Nature Communications.

Normally phages, like the WO phage that they studied, carry specialized genes that break open and defeat the defenses of the prokaryotic bacterial cells they target. But in this case, "the portion of DNA related to the black widow spider toxin gene is intact and widespread in the phage," said Bordenstein. "There is also evidence that the phage makes insecticidal toxins, but we are not certain yet how these are utilized and administered."

The scientists also found that WO shares a number of other segments of DNA with animal genomes. These include a sequence that the eukaryotic cells found in animals use to sense pathogens, which is also involved in triggering cell death. In addition, there were several genes that the cells use to evade immune responses. "These sequences are more typical of eukaryotic viruses, not phages," Bordenstein commented.

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