Cats have been fighting feline immunodeficiency virus (FIV) for at least 60,000 years. Researchers have found evidence of an ancient arms race between the species known today as domestic cats (Felis silvestris catus) and the virus in a protein that helps stop FIV from replicating.
FIV usually breaks down APOBEC3Z3, allowing the virus to keep infecting cells. But cats have evolved a protein variant, called haplotype V, which 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.