EARLY SUPPRESSION OF SIV REPLICATION BY CD8-SPECIFIC CYTOTOXIC T-CELLS IN VACCINATED MACAQUES( NEF)

In order to develop a successful subunit vaccine against infection wit h the human immunodeficiency virus (HIV), protective immune effector f unctions must be identified. Until now, there has been only indirect e vidence that HIV-specific cytotoxic T lymphocytes (CTLs) fulfill this role. Using the macaque simian immunodeficiency virus (SIV) model, the protective potential of nef-specific CTLs, stimulated by vaccination, was examined in animals challenged with a high intravenous dose of th e pathogenic simian immunodeficiency virus, SIVmac251(32H)(pJ5). An in verse correlation was found between the vaccine-induced nef-specific C TL precursor frequency and virus load measured after challenge. In add ition, the early decline in viraemia, observed in both vaccinated and unvaccinated control animals was associated with the development of vi rus-specific CTL activity and not with the presence of virus-specific neutralizing; antibodies. The results imply that vaccines that stimula te strong CTL responses could protect against HIV infection.