Human immunodeficiency virus envelope glycoprotein variable 1 and variable 2 region (HIV Env V1V2 region)

The HIV envelope glycoprotein V1V2 region is a highly variable, heavily glycosylated domain located at the apex of the gp120 subunit of the HIV-1 envelope trimer. It forms either a four-stranded or five-stranded beta-sheet structure, depending on its conformation, and stabilizes the trimeric gp120 spike. V1V2 shields the variable V3 loop and coreceptor/CD4 binding sites before receptor engagement and exposes them after, allowing viral entry. It harbors key motifs, such as the α4β7 integrin–binding sequence, relevant for both structural stability and immune recognition. V1V2 is a major determinant of immune evasion via extensive glycan shielding and sequence variation, but is also an important vaccine target: the RV144 trial found antibodies to this region correlated with decreased HIV-1 infection risk but did not mediate strong or broadly neutralizing effects. Multiple monoclonal antibodies, including PG9, PG16, CH04, PGT145, and 830A, directly target V1V2 glycan-dependent epitopes and serve as both research tools and therapeutic prototypes. Overall, the V1V2 region is central to HIV-1 infectivity, pathogenesis, and challenges in vaccine and antibody-based therapy.

Other names

V1/V2 region of HIV-1 gp120V1V2 loopHIV-1 Env V1V2gp120 variable regions 1 and 2V1V2 domainV1V2 apex

Antibody-mediated neutralization (binding to V1V2 blocks HIV-1 attachment and entry, disables masking of conserved regions, enables immune clearance). Conformational interference (disrupting V1V2 structure or its shielding effect on other functional domains).