A virus that infects bacteria shares DNA sequences with animals, including the black widow spider, finds a study published in Nature Communications this week.
Viruses that infect bacteria do not also infect eukaryotes (i.e. animals, plants, fungi and protists). Although viruses commonly exchange genetic material with their hosts, viruses have not been known to assimilate genes from a domain of life different from that of their host.
Sarah Bordenstein and Seth Bordenstein sequenced the genome of phage WO, a virus that infects the bacteria Wolbachia, and found that a section of the genome is made up of eukaryotic-like genes. The genes are closely related to insect and spider genes for toxins, mediating host-microbe interactions, host cell suicide, and transport across cell membranes. Since Wolbachia itself infects insect and spider cells, the authors suggest that these genes may help the virus infiltrate animal cells to reach the bacteria.
Based on their eukaryotic characteristics and distribution among animals, the genes probably originated in animals before being incorporated by the virus. However, the direction and route of DNA transmission between animal and virus is still uncertain.