Millions of people suffer from autoimmunity and the prevalence continues to rise. For most autoimmune diseases, the cause is unknown but viral infections are suspected to play a role. Despite this link, there is limited data demonstrating a direct causal role for viral infection in autoimmune disease. We have found that neonatal infection with roseolovirus induces autoimmunity by disrupting the processes that normally limit the development of autoreactive T and B cells. Our initial studies suggest that this occurs due to infection of the thymus. The Bigley lab is focused on understanding the mechanism by which roseoloviruses induce autoimmunity. We are also studying other herpesviruses and thymotropic viruses to understand if thymic infection induced autoimmunity is specific to roseolovirus or might be shared amongst other viruses. Finally, we are using immunologic tools and molecular virology to understand what long-term impact thymic infections have on immune cells, as well as host virus interactions that alter immunologic tolerance.