The central theme to my research is the adaptive immune response of humans to retrovirus infections. I am conducting projects in two clinical contexts. The first is HIV pediatric infection, in which virus-specific responses are generated by an immature immune system and in the presence of an immunosuppressive virus. The second context is the cross-species transmission of simian foamy retroviruses from apes and monkeys to humans. These viruses can establish a persistent infection in the new human host, but they have not emerged into the human population, probably because of effective restriction by the immune system.