High Antigenic Cross-Reactivity of the V3 Consensus Sequences of HIV-1 gp120

The principal neutralization determinant (PND) of the human immunodeficiency virus type 1 (HIV-1) is located within the variable V3 region of the external envelope protein gp 120. Although it is recognized that V3 sequences induce antibody response with restricted neutralization activity in vitro , we observed that the V3 consensus sequences representing North American/European and African isolates were highly cross-reactive, binding 94 and 77%, respectively, of sera collected from HIV-1 individuals originating from various parts of the world. Even HIV-1-positive sera from some East African residents, infected by strains whose V3 loop sequences are undoubtedly distinct from the North American/European consensus V3 loop sequence, reacted better to the V3 North American/European consensus peptide than to African-specific V3 sequences. Results indicate that the V3 consensus sequences represent the best candidates for optimal cross-reactivity with a wide variety of strains. Furthermore, using immunoassays for antibodies to prototype-specific V3 sequences, it is shown that HIV-1 strains related to the MN group are prevalent in West Africa, indicating either a West African origin of the MN-related viruses or more probably an introduction of this group of viruses through European/North American contacts.