Induction of antibodies to the human immunodeficiency virus type 1 by immunization of baboons with immunoglobulin molecules carrying the principal neutralizing determinant of the envelope protein.

The hypervariable region 3 (V3) within the disulfide-bridged loop of the envelope protein of the human immunodeficiency virus type 1 (HIV-1) contains an amino acid sequence that was defined as a principal neutralizing determinant (PND). A 19-amino acid residue consensus sequence (designated V3C) predicted from the PND sequences of 245 isolates as well as a sequence from the PND of the WMJ2 HIV-1 isolate (designated V3M) were expressed on the variable region of murine-human immunoglobulin (Ig) chimeras that were designated Ig-V3C and Ig-V3M, respectively. The HIV-1 sequences on the Ig chimeras preserved their antigenicity and interacted with antibodies specific for peptides encompassing the V3C and V3M sequences. In baboons, Ig-V3C and Ig-V3M induced antibodies that bound V3C and V3M peptides as well as the glycoprotein gp120 envelope protein of HIV-1 MN isolate. In addition, the baboons' antisera were able to prevent infection of CD4 SupT1 susceptible T cells by HIV-1 MN. Finally, Ig-V3M chimeras were able to stimulate in vitro production of antibodies specific for the HIV-1 envelope-derived peptides by lymphocytes from HIV-1-infected human subjects.