IMMUNIZATION OF MACAQUES WITH SIV ENV RECOMBINANTS - SPECIFICITY OF T-CELL AND ANTIBODY-RESPONSES AND EVALUATION OF PROTECTIVE EFFICACY

Macaques were immunised with lentil lectin purified recombinant SIVmac (BK28) derived gp160 (rgp160) with or without live vaccinia (vac)-env (BK28) priming, followed by a final boost with solid matrix antibody antigen (SMAA)-gp160 (J5) complexes and challenged with the SIVmac mol ecularly cloned virus J5M. Rgp160 and vac-env plus gp160 induced stron g Ab responses against the homologous virus. Live vac-env did not enha nce or prolong the antibody response, however, T cell responses were s tronger. Analysis of the specificity of the immune response demonstrat ed that sequence variation within SIVmac viruses can affect antibody a nd T cell recognition. A single booster immunisation with the heterolo gous SIVmac J5 env recombinant protein was not sufficient to protect a gainst the molecularly cloned virus J5M. These findings further illust rate the difficulty of generating protective immunity with immunogens based on single sequence recombinants.