The Varble Lab studies the viruses that infect bacteria, bacteriophage. Bacteriophages are inextricably linked to the bacteria they infect, shaping their life cycle, pathogenicity, and genomes. We study how these viruses infect bacteria and how bacteria defend against these infections, with a focus on the adaptive bacterial immune response, the CRISPR-Cas system. As bacteria have increasingly gained resistance to antibiotics, bacteriophage have also been explored as an alternative approach to treating infections, termed phage therapy. Staphylococcus aureus is an important human pathogen of great concern due to its ability to rapidly evolve resistance to current antibiotics. A current focus of the lab is identifying novel phages that can infect S. aureus and characterizing their potential as therapeutics.