Safety and immunogenicity of a live recombinant canarypox virus expressingHIV type 1 gp120 MN tm/gag/protease LAI (ALVAC-HIV, vCP205) followed by a p24E-V3 MN synthetic peptide (CLTB-36) administered in healthy volunteers at low risk for HIV infection

A live recombinant canarypox vector expressing HIV-1 gp120 MN tm/gag/protea se LAI (ALVAC-HIV, vCP205) alone or boosted by a p24E-V3 MN synthetic pepti de (CLTB-36) was tested in healthy volunteers at low risk for HIV infection for their safety and immunogenicity, Both antigens were well tolerated. AL VAC-HIV (vCP205) induced low levels of neutralizing antibodies against HIV- 1 MN in 33% of the volunteers. None of them had detectable neutralizing ant ibodies against a nonsyncytium-inducing HIV-1 clade B primary isolate (Bx08 ). After the fourth injection of vCP205, CTL activity was detected in 33% o f the volunteers and was directed against Env, Gag, and Pol, This activity was mediated by both CD4(+) and CD8(+) lymphocytes, On the other hand, the CLTB-36 peptide was poorly immunogenic and induced no neutralizing antibodi es or CTLs. Although the ALVAC-HIV (vCP205) and CLTB-36 prime-boost regimen was not optimal, further studies with ALVAC-HIV (vCP205) are warranted bec ause of its clear induction of a cellular immune response and utility as a priming agent for other subunit antigens such as envelope glycoproteins, ps eudoparticles, or new peptides.