Talk: The viral authors of evolution

Viruses are the most numerous and diverse biological entities on the planet. Their constant predation of hosts drives the diversification of defense and counter-defense systems in an endless genetic conflict for cellular resources. A subset of viruses and defense systems function as wild genome “authors” through evolved strategies to physically integrate foreign nucleic acid into the host genome. In this seminar, I will discuss how one such wild genome author used by CRISPR-Cas defense systems folds the genome to insert foreign nucleic acid into a precise location genome for CRISPR-mediated viral defense. Though some defense systems rely on genomic integration for successful defense, far more viruses and genetic parasites use genome integration as a replication strategy. I will also discuss a rare but important evolutionary outcome of viral integration. In five independent instances, viral integration in the germline of an ancient vertebrate gave rise to genes and gene families that are now essential in modern mammals.