His research focuses on host-virus interactions, especially as it relates to the consequences of infection. For the past several years He has studied the chloroviruses, which are evolutionarily related to other large DNA viruses, such as asfar, asco, irido, marseille, mimi and pox viruses; collectively known as “giant viruses”. He is investigating many aspects of chloroviruses including the virion structure and function; genome structure, function and evolution; metabolic changes associated with infections, as well as the role of algal viruses in aquatic ecosystems.