Proliferation of latently infected CD4+ T cells with replication-competent proviruses is an important mechanism contributing to HIV persistence during antiretroviral therapy (ART). One approach to targeting this latent cell expansion is to inhibit mTOR, a regulatory kinase involved with cell growth, metabolism, and proliferation. Here, we determined the effects of chronic mTOR inhibition with rapamycin with or without T cell activation in SIV-infected rhesus macaques (RMs) on ART. Rapamycin perturbed the expression of multiple genes and signaling pathways important for cellular proliferation and substantially decreased the frequency of proliferating CD4+ memory T cells (TM cells) in blood and tissues. However, levels of cell-associated SIV DNA and SIV RNA were not markedly different between rapamycin-treated RMs and controls during ART. T cell activation with an anti-CD3LALA antibody induced increases in SIV RNA in plasma of RMs on rapamycin, consistent with SIV production. However, upon ART cessation, both rapamycin and CD3LALA–treated and control-treated RMs rebounded in less than 12 days, with no difference in the time to viral rebound or post-ART viral load set points. These results indicate that, while rapamycin can decrease the proliferation of CD4+ TM cells, chronic mTOR inhibition alone or in combination with T cell activation was not sufficient to disrupt the stability of the SIV reservoir.
Benjamin D. Varco-Merth, William Brantley, Alejandra Marenco, Derick D. Duell, Devin N. Fachko, Brian Richardson, Kathleen Busman-Sahay, Danica Shao, Walter Flores, Kathleen Engelman, Yoshinori Fukazawa, Scott W. Wong, Rebecca L. Skalsky, Jeremy Smedley, Michael K. Axthelm, Jeffrey D. Lifson, Jacob D. Estes, Paul T. Edlefsen, Louis J. Picker, Cheryl M.A. Cameron, Timothy J. Henrich, Afam A. Okoye
Plasma and cell-associated viral loads were equivalent between study groups prior to rapamycin treatment.