We investigate virus-host interactions. Human cytomegalovirus (HCMV) is a herpesvirus that is prevalent in the population, where it remains latent, or quiet, in the host for life. However, when an individual’s immune system is weakened or dysregulated, the virus can reawaken, or reactivate, to cause severe complications and often death. Dr. O’Connor’s research focuses on the processes that balance the silenced and active phases of the virus, as well as how reactivation leads to viral pathogenesis and disease progression.