IMMUNIZATION WITH VIRION-DERIVED GLYCOPROTEIN-130 FROM HIV-2 OR SIV PROTECTS MACAQUES AGAINST CHALLENGE VIRUS GROWN IN HUMAN OR SIMIAN CELLS OR PREPARED EX-VIVO

We have compared in the macaque model the efficacy of the virion-deriv ed glycoprotein of HIV-2ben (HIV-2 gp130) with that of SIVmac251/32H ( SIV gp130). The latter-vaccination trial was in part combined with vac cinia virus (VV) priming. Both antigen preparations induced a strong h umoral, but a weak cellular, immune response. The first challenge was performed with autologous virus grown on a human T cell line. More tha n 50% of the monkeys immunized with HIV-2 gp130 (five of nine) and 63% of the monkeys immunized with SIV gp130 (five of eight) were protecte d. All such protected animals received one or two booster immunization s before they were rechallenged either with heterologous HIV-2(SBL6669 ) grown on monkey peripheral blood mononuclear cells or with an ex viv o stock of SIVmac251/32H prepared from the spleen of an SIV-infected m acaque and not passaged in vitro. Immunization with HIV-2 gp130 did no t protect against the second challenge, but one animal showed limited infection as indicated by positive PCR only. Challenge of the SIV gp13 0-immunized monkeys with the spleen-derived virus led to infection of three animals; remarkably, one of these was only PCR positive. Two ani mals were completely protected. Thereby we can exclude the influence o f cellular proteins on protective immunity. Priming with VV was not su perior to immunization with gp130 alone. Neither at the first nor at t he second challenge were the virus-specific humoral and cellular immun e responses of the vaccinees clearly correlated with protection. Howev er, neutralizing antibodies may have been important in the SIV gp130-i mmunized animals at first challenge.