Ancient origins of endogenous retroviruses in Metazoans

Abstract

AbstractEndogenous retroviruses (ERVs) are generally seen as remnants of past retroviral infections, but some can make new germline insertions that are transmitted across generations. ERVs can carry membrane fusion glycoproteins, orenvgenes, which allow them to remain infectious. We systematically searched for such active ERVs containingenvin metazoan genomes and found that they are ubiquitously present across taxa including ancient animals such as Cnidarians, Ctenophores and Tunicates. Phylogenetic analyses revealed that the divergence of ERVs, including those found in vertebrate and insect genomes, largely follow the divergence of host organisms, indicating that they share a common and highly ancient origin, and that they survive over time primarily through vertical transfer.