Studying his cohort of elite controllers, in collaboration with others, Deeks has looked at genetic and functional characteristics of the T-lymphocyte response to HIV infection. They chose to focus on this arm of the immune system first, as it is well known that the so-called “adaptive” T cell immune response is the primary mechanism that humans use to prevent or control chronic infections. Although many elite controllers had clear evidence of potent HIV-specific T cell immunity, a surprising number failed to exhibit such a response.