CD8+ Lymphocytes Are Required for Maintaining Viral Suppression in SIV-Infected Macaques Treated with Short-Term Antiretroviral Therapy

Infection with HIV persists despite suppressive anti-retroviral therapy (ART), and treatment interruption results in rapid viral rebound. Antibody-mediated CD8(+) lymphocyte depletion in simian immunodeficiency virus (SIV)-infected rhesus macaques (RMs) shows that these cells contribute to viral control in untreated animals. However, the contribution of CD8(+) lymphocytes to maintaining viral suppression under ART remains unknown. Here, we have shown that in SIV-infected RMs treated with short-term (i.e., 8-32 week) ART, depletion of CD8(+) lymphocytes resulted in increased plasma viremia in all animals and that repopulation of CD8(+) T cells was associated with prompt reestablishment of virus control. Although the number of SIV-DNA-positive cells remained unchanged after CD8 depletion and reconstitution, the frequency of SIV-infected CD4(+) T cells before depletion positively correlated with both the peak and area under the curve of viremia after depletion. These results suggest a role for CD8(+) T cells in controlling viral production during ART, thus providing a rationale for exploring immunotherapeutic approaches in ART-treated HIV-infected individuals.