Immunogenicity and protective efficacy of a human immunodeficiency virus type 2 recombinant canarypox (ALVAC) vaccine candidate in cynomolgus monkeys

The efficacy of a recombinant human immunodeficiency virus (HIV) type 2 canarypox (ALVAC HIV-2) vaccine candidate given alone or in combination with HIV-2 envelope gp125 or HIV-2 V3 synthetic peptides was investigated in 14 cynomolgus monkeys, High antibody titers to HIV-2 gp125 were demonstrated in monkeys given booster immunizations with gp125, Neutralizing antibody titers were low (less than or equal to 20) in all monkeys except 2. Significant lymphocyte proliferative responses to killed HIV-2 virions were observed in monkeys given booster immunizations with gp125, HIV-2-specific cytotoxic T lymphocytes were demonstrated prior to viral challenge in 3 of 12 monkeys, After challenge with homologous cell-free HIV-2 propagated in monkey cells, 4 of 10 monkeys immunized with ALVAC HIV-2 plus HIV-2 gp125 or V3 peptides were protected, as determined by negative virus isolation and polymerase chain reaction for viral DNA, Four monkeys immunized with ALVAC HIV-2 alone were not protected. All 12 control monkeys became infected, There was no correlation between the immunologic parameters studied and protection against infection in the vaccinated monkeys.