Long-term protection against SIV-induced disease in macaques vaccinated with a live attenuated HIV-2 vaccine.

The aim of this study was to test the ability of a live attenuated human immunodeficiency virus type 2 (HIV-2) vaccine to protect cynomolgus monkeys against superinfection with a pathogenic simian immunodeficiency virus (SIVsm). This report is an update on our previously reported observation period of nine months. The new data here show that three of four monkeys vaccinated with live HIV-2 were protected against immunosuppression and SIV-induced disease during more than five years of follow-up. The quality of the immunity was permissive for infection, but monkeys that survived showed restricted viral replication in peripheral blood and lymph nodes. This study shows that it is possible to induce protection against a pathogenic heterologous primate lentivirus and to prevent disease in vaccinated monkeys even if infection is not prevented. These findings provide evidence that protection against AIDS can be achieved by immunization.