Epitope Mapping and Topology of Baculovirus-Expressed HIV-1 gp160 Determined with a Panel of Murine Monoclonal Antibodies

To define protein folding patterns of HIV-1 Env subunit vaccines, we have isolated a set of 30 monoclonal antibodies (MAbs) from BALB/c mice immunized with a recombinant gp160 vaccine (rgp160) expressed in a baculovirus system. This article describes epitope mapping for the MAb panel and topology of the epitopes for rgp160 and a recombinant gp120 (rgp120) also expressed in a baculovirus system. The following results are reported: (1) rgp160 harbors a minimum of 4 antigenic domains, 3 mapping to the C1, C2, and C3/V4 regions of gp120 and 1 mapping to the cytoplasmic tail of gp41; (2) there are at least 3 adjacent or overlapping epitopes in each antigenic domain; (3) a minimum of 14 independent epitopes were mapped, all of which are continuous sites; (4) each of the epitopes is exposed on rgp160 without prior manipulation of the protein; and (5) by contrast, 6 of the 8 epitopes mapping to the C1, C2, and C3/V4 regions arenot exposed on rgp120, but become exposed when the protein is denatured. Taken together...