Persisting Viral Sequences Shape Microbial CRISPR-based Immunity. - Ariel D. Weinberger; Christine L. Sun; Mateusz M. Plucinski; Vincent J. Denef; Brian C. Thomas; Philippe Horvath; Rodolphe Barrangou; Michael S. Gilmore; Wayne M. Getz; Jillian F. Banfield (PLoS Comput. Biol., 2012)