HUMORAL AND CELL-MEDIATED-IMMUNITY IN RABBITS IMMUNIZED WITH LIVE NONREPLICATING AVIPOX RECOMBINANTS EXPRESSING THE HIV-1(SF2) ENV GENE

The canarypox (CP) and fowl pox (FP) viruses, which are unable to repl icate productively in non-avian species, have been utilized as live ve ctors carrying the HIV-1(SF2) env gene with the putative immunosuppres sive (IS) region complete (CPIS+ and FPIS+) or deleted (CPIS- and FPIS -), To determine if these avipox-env recombinants could be utilized to elicit a specific immune response against HIV-1, six groups of rabbit s were immunized with CPIS+, CPIS-, FPIS+, FPIS- constructs or their n on-engineered wild-type CPwt or FPwt, counterparts. After a primary in oculation and successive boosters, env-specific humoral and cell-media ted immunity were demonstrated by ELISA, immunoblots and lymphoprolife ration assays. Antibody titres and neutralization activities were high er in CP- than FP-inoculated rabbits, the CPIS+ always showing a simil ar immunogenic capacity to CPIS-. Evidence is also presented indicatin g that rabbit sera possess group-specific antibodies, which were, howe ver, unable to cross-neutralize divergent HIV-1 strains. Although the protective capacity against HIV-1 experimental infection has not yet b een determined in these animals, our results suggest that these recomb inants might represent promising and safer candidate vaccines against HIV-1.