POSITIVE ROLE OF MACAQUE CYTOTOXIC T-LYMPHOCYTES DURING SIV INFECTION- DECREASE OF CELLULAR VIREMIA AND INCREASE ASYMPTOMATIC CLINICAL PERIOD

We have measured cellular viremia and observed clinical outcome of mac aques from two cohorts, the first including 12 macaques infected by SI Vmac251 and the second including 12 macaques immunized by lipopeptides and then challenged by SIVmac251. In the first cohort (SIV-infected m acaques), 3 patterns of CTL responders were determined: high, low and non-responders. In the macaques belonging to pattern of low and non-re sponders, cellular viremia, measured by growing the virus from PBMC, w as continuously high during the first 6 months after infection, and fi ve macaques developed AIDS within 14.4+/-7.7 months. Conversely, in th e six high-responder macaques, cellular viremia was constantly low and only one macaque developed AIDS at 19 months, the five others being a live at 24 months. After immunization with lipopeptides, 7/12 macaques showed CTL responses and among these, after SIV challenge, cellular v iremia was continually low, and no disease was observed at 22 months o f follow-up. Conversely, the five non-responder macaques displayed per sistent high viremia and macaques developed AIDS within 12.6+/-2.9 mon ths after SIV challenge. These data strongly suggest that the presence of cytotoxic responses is inversely correlated with cellular viremia and correlated with overall survival and thus is an important componen t of the immune response in vaccinated individuals. It supports the id ea that a strengthening of the CTL responses, if possible, might be be neficial in HIV-infected human beings.