FAILURE OF A HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 (HIV-1) SUBTYPE B-DERIVED VACCINE TO PREVENT INFECTION OF CHIMPANZEES BY AN HIV-1 SUBTYPE-E STRAIN

Generation of an effective vaccine against human immunodeficiency viru s type I (HIV-1) must overcome problems associated with extensive gene tic diversity. Although we previously reported vaccine-induced protect ion of chimpanzees against infection with an HIV-1 strain different fr om the one used to make the immunogens, both the HIV-1 vaccine and cha llenge strains were classified within subtype B. To determine whether the HIV-1-specific immunity elicited might also prevent infection by a strain of HIV-1 from a different clade, the same chimpanzees were giv en booster inoculations with the rgp160-MN/LAI (recombinant hybrid gp1 60 molecule) and V3-MN immunogens and then were challenged by intraven ous inoculation of a comparable dose of a subtype E HIV-1 from the Cen tral African Republic Both animals became infected with the subtype E virus. indicating that intraclade vaccine-mediated protection does not predict interclade protection, at least in the contest of intravenous challenge and the HIV-1 strains used. This study has important implic ations for planned phase III efficacy trials of similar vaccine prepar ations in Thailand where HIV-1 subtype B and E strains cocirculate.