HIV-specific T cell responses reflect substantive in vivo interactions with antigen despite long-term therapy
Eva M. Stevenson, Adam R. Ward, Ronald Truong, Allison S. Thomas, Szu-Han Huang, Thomas R. Dilling, Sandra Terry, John Bui, Talia M. Mota, Ali Danesh, Guinevere Q. Lee, Andrea Gramatica, Pragya Khadka, Winiffer D. Conce Alberto, Rajesh T. Gandhi, Deborah K. McMahon, Christina M. Lalama, Ronald J. Bosch, Bernard Macatangay, Joshua C. Cyktor, Joseph J. Eron, John W. Mellors, R. Brad Jones
Abstract
Antiretroviral therapies (ARTs) abrogate HIV replication; however, infection persists as long-lived reservoirs of infected cells with integrated proviruses, which reseed replication if ART is interrupted. A central tenet of our current understanding of this persistence is that infected cells are shielded from immune recognition and elimination through a lack of antigen expression from proviruses. Efforts to cure HIV infection have therefore focused on reactivating latent proviruses to enable immune-mediated clearance, but these have yet to succeed in reducing viral reservoirs. Here, we revisited the question of whether HIV reservoirs are predominately immunologically silent from a new angle: by querying the dynamics of HIV-specific T cell responses over long-term ART for evidence of ongoing recognition of HIV-infected cells. In longitudinal assessments, we show that the rates of change in persisting HIV Nef-specific responses, but not responses to other HIV gene products, were associated with residual frequencies of infected cells. These Nef-specific responses were highly stable over time and disproportionately exhibited a cytotoxic, effector functional profile, indicative of recent in vivo recognition of HIV antigens. These results indicate substantial visibility of the HIV-infected cells to T cells on stable ART, presenting both opportunities and challenges for the development of therapeutic approaches to curing infection.