8th International AIDS Conference Amsterdam, Netherlands — July 19-24, 1992

Int Conf AIDS 1992 Jul 19-24; 8:We52 (abstract no. WeD 1042)
De Vries P, Heeney J, Morein B, Osterhaus AD; Laboratory of Immunobiology, RIVM, Bilthoven, The Netherlands.

OBJECTIVES: Comparison of protection afforded by iscome and MDP adjuvanted whole inactivated virus in a SIV-macaque model.

METHODS: Eight macaques (Macaca mulatta) were vaccinated four times with an SIV iscom vaccine, eight with an MDP adjuvanted whole inactivated SIV vaccine, four with a measles virus (MV) iscom vaccine and four with an MDP adjuvanted inactivated whole MV vaccine. They were all challenged with either 10MID50 of the homologous cell-free SIVmac251 (32H) propagated in C8166 cells or with 10MID50 of SIV-infected PBMC directly taken from a monkey suffering from AIDS after infection with the SIVmac251 (32H) strain.

RESULTS: All the monkeys vaccinated with SIV-MDP and SIV-iscom and challenged with cell-free SIVmac251 (32H) were protected from developing SIV viraemia, whereas all the MV-MDP and MV-iscom vaccinated monkeys developed SIV-viraemia within four weeks after cell-free challenge. Also all the MV-MDP and MV-iscom vaccinated animals challenged with SIV infected PBMC developed viraemia within 2 weeks. Two out of four SIV-MDP vaccinated and two out of four SIV-iscom vaccinated monkeys challenged with SIV infected PBMC were protected from SIV viraemia. The data were confirmed by serological tests and PCR analyses.

CONCLUSION: This is the first demonstration that vaccination can protect macaques from challenge with SIV infected PBMC. This protection should be attributed to immunization with SIV-specific antigens since the challenge was carried out directly with SIV infected PBMC of the homologous species.

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