The O’Connor lab studies bacterial pathogenesis, with a focus on the mechanisms by which bacterial pathogens establish infection, how they exploit host cell machinery to accomplish this, and how individual virulence proteins and their component pathways coordinately contribute to disease. In parallel, we investigate how virulence strategies arise in environmental reservoirs as a consequence of bacterial interactions with protozoa and the role of these natural hosts in driving the transition of pathogens from environmental reservoirs to humans.