Several antigenic determinants exposed on the gp120 moiety of HIV-1 gp160 are hidden on the mature gp120.

Mouse mAb reactive to the HIV-1 envelope glycoprotein precursor gp160 of the HTLVIII(B) isolate were characterized in radioimmunoprecipitation and immunoblot tests with the use of HTLVIII(B) isolate as Ag. The reactivities of these mAb were also measured in a capture enzyme immunoassay and in radioimmunoprecipitation assay by using gp160 and gp120 expressed as vaccinia recombinants. Striking differences in exposure of specific epitopes were noted between the gp120 component of the gp160 precursor and the fully processed gp120 in both tests. These conformational rearrangements affecting the gp120 moiety of the HIV-1 envelope glycoprotein might have important implications on its immunogenicity.