Cat-versus-virus arms race goes back millennia

Cats have been fighting feline immuno­deficiency virus, or FIV, for at least 60,000 years. In a feline protein that helps stop FIV replication, researchers have found evidence of an ancient arms race between Felis silvestris catus, the species familiar today as the domestic cat, and the virus.

Domestic cats carry seven different versions, or haplotypes, of this protein, called APOBEC3Z3. But it’s unclear how each version affects cats’ ability to fight the virus.

FIV breaks down most versions of APOBEC3Z3, allowing the virus to keep infecting cells. But one variant of the protein, haplotype V, staves off destruction, Rokusuke Yoshikawa of Kyoto University in Japan and colleagues report online October 21 in the Journal of Virology.

By their calculations, haplotype V is at least 60,000 years old, which means the ancestors of domestic cats had already encountered a primitive version of FIV long before cats were domesticated about 10,000 years ago.