The focus of Dr. Roy's research is to understand the molecular and cellular events that enable microbial pathogens to evade host defense mechanisms. In particular, he is interested in how bacteria that replicate inside mammalian cells create specialized vacuoles that support pathogen replication. He has been using Legionella pneumophila and Coxiella burnetii as model pathogens to study this process. Both pathogens use a type IV secretion system called Dot/Icm to delivers bacterial effector proteins into the eukaryotic host cell cytosol. He is using multidisciplinary approaches to characterize the origin and function of these effector proteins. The goal is to determine the mechanism by which these bacterial effector proteins regulate membrane transport, modulate host immunity, and subvert eukaryotic cell functions important for intracellular survival.