A Reptilian Endogenous Foamy Virus Sheds Light on the Early Evolution of Retroviruses

Abstract

Endogenous retroviruses (ERVs) can be thought of as host genomic fossils of ancient viruses. Foamy viruses, including those that form endogenous copies, provide strong evidence for virus-host co-divergence across the vertebrate phylogeny. Endogenous foamy viruses (EFV) have previously been discovered in mammals, amphibians and fish. Here we report a novel endogenous foamy virus, named SpuEFV, in genome of the tuatara (Sphenodon punctatus), an endangered reptile species endemic to New Zealand. Phylogenetic analyses revealed that SpuEFV has likely co-diverged with its host over a period of many millions of years. The discovery of SpuEFV fills a major gap in the fossil record of foamy viruses and provides important insights into the early evolution of retroviruses.