Research published in the Proceedings of the National Academy of Sciences found that some individuals exposed to HIV-1, but who remain uninfected, have a certain pattern of virus-specific immune responses that differentiated them from individuals who became infected. The findings build upon prior research by studying these responses in the context of a controlled clinical trial, examining a large number of subjects, and by having access to specimens saved before anyone was infected. In the future, this information could be used to assess HIV-1 infection risk or inform the design of a preventative HIV-1 vaccine.The finding suggests that such immune responses may play a role in blocking systemic infection after exposure to the virus.

"Demonstrating HIV protection associated with vaccine or, as in this case, exposure-induced immunity is a very high bar to achieve, and appropriately so. Our findings indicate that the host immune system interfaces with the virus or its proteins more commonly than previously thought, generating naturally induced immunity in the form of T-cell responses that contribute to a persistent HIV negative status in some exposed people. Only with additional research can we truly know if these immune responses can be induced by a vaccine candidate, and whether vaccine-induced responses provide protection," according to Dr. Esper Kallas, of USP, co-senior author of the manuscript.