Pre-Cambrian Origin of Retrotransposons with Viral Envelopes Discovered in Metazoans

A new study published in eLife reveals the widespread presence and deep evolutionary history of envelope-carrying Ty3/gypsy retrotransposons across invertebrate metazoan genomes, including ancient animals like cnidarians and ctenophores. This discovery suggests that these elements independently acquired membrane fusion proteins early in metazoan evolution, potentially predating the bilaterian-non-bilaterian split, offering significant insights into the origins of retroviruses and retroelement-envelope associations.