HIV-1 vaccine-induced immune responses which correlate with protection from SHIV infection: compiled preclinical efficacy data from trials with ten different HIV-1 vaccine candidates

The specific immune mechanisms necessary and/or sufficient to elicit HIV-va ccine protection remain undefined. Utilising the SHIV rhesus macaque model the immunogenicity as well as the efficacy of ten different HIV-1 vaccine c andidates was evaluated. Comparison of the immune responses induced, with t he ability of the vaccine to protect from SHIV infection provided a means t o determine which type of immune responses were necessary for protection. V accine candidates included VLPs, DNA, subunit protein with novel adjuvant f ormulations, ISCOMs and pox-virus vectors. Protection from SHIV infection w as achieved in approximately half of the animals which received a primary i ntravenous cell-free challenge. The presence of CTL in the absence of other effector responses did not correlate with protection from this route and t ype of challenge. Virus neutralising antibodies (Nab) appeared to be necess ary but alone were insufficient for protection. If Ag-specific IFN-gamma an d/or IL-4 as well as lymphoproliferative (LP) responses were found with the lack of a detectable IL-2 response, then protection was not observed. Immu nity correlated with the magnitude of Nab responses, beta-chemokines and as well as balanced, qualitative T-helper responses. (C) 1999 Elsevier Scienc e B.V. All rights reserved.