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 h ave isolated a set of 30 monoclonal antibodies (MAbs) from BALB/c mice immunized with a recombinant gp160 vaccine (rgp160) expressed in a ba culovirus system. This article describes epitope mapping for the MAb p anel 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 m apping 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 overlap ping epitopes in each antigenic domain; (3) a minimum of 14 independen t epitopes were mapped, ah of which are continuous sites; (4) each of the epitopes is exposed on rgp160 without prior manipulation of the pr otein; 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 t he protein is denatured. Taken together, these results show that rgp16 0 and rgp120 are folded differently, illustrating the use of this MAb panel to compare epitope topographies of recombination HIV-I Env prote ins. This MAb panel may aid in the refinement of HIV-1 Env subunit vac cines.