Work in our laboratory combines traditional, molecular virology with evolutionary genetics, in order to study how viruses adapt to their hosts. Our goal is to understand how virus evolution is influenced by genetic variation both within host populations (polymorphism) and between host species (divergence). Current projects in the laboratory focus on retroviruses, specifically the lentiviruses of humans and their primate relatives (the human and simian immunodeficiency viruses – HIV and SIV). Among other things, we are interested in the interactions between these viruses and host genes that act as genetic barriers to cross-species transmission (also known as restriction factors), and in understanding how viruses adapt to new genetic environments once a species barrier has been breeched. We are also interested in how lentiviruses adapt within individuals, particularly in response to shifting selective pressures imposed by virus-specific polyclonal antibody responses.