Immunisation of macaques with SIV env recombinants: specificity of T cell and antibody responses and evaluation of protective efficacy

Abstract

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 molecularly cloned virus J5M. Rgp160 and vac-env plus gp160 induced strong Ab responses against the homologous virus. Live vac-env did not enhance or prolong the antibody response, however, T cell responses were stronger. Analysis of the specificity of the immune response demonstrated that sequence variation within SIVmac viruses can affect antibody and T cell recognition. A single booster immunisation with the heterologous SIVmac J5 env recombinant protein was not sufficient to protect against the molecularly cloned virus J5M. These findings further illustrate the difficulty of generating protective immunity with immunogens based on single sequence recombinants.