Human immunodeficiency virus envelope glycoprotein gp120 V3 region (HIV-1 gp120 V3 region)

The gp120 V3 region is a highly immunogenic, structurally flexible segment (about 35 amino acids) within the HIV-1 envelope glycoprotein gp120, crucial for binding cellular co-receptors such as CCR5 and CXCR4 to mediate viral entry. Although its sequence varies markedly among HIV subtypes, conserved structural motifs at the V3 tip are essential for interaction with host cell receptors and thus determine viral tropism and infectivity[1][3][5][8]. Its exposure following CD4 binding makes it the principal neutralizing determinant in natural and vaccine-induced immunity—anti-V3 antibodies are prevalent in infected individuals. The V3 loop’s variable surface and conformational flexibility are major obstacles for broadly neutralizing antibody and vaccine design, as well as sources of therapeutic resistance. The V3 region is also used as a biomarker to assess co-receptor usage and guide therapy with entry inhibitors targeting CCR5[7]. This molecule is not a human receptor or enzyme, but rather a critical segment of the HIV-1 envelope that serves as a therapeutic target for neutralizing antibodies and entry inhibitors aimed at blocking viral infection of host cells.

Other names

HIV-1 V3 loopgp120 V3 loopV3 region of HIV-1 gp120Principal neutralizing determinant (PND)

Drugs block co-receptor (CCR5/CXCR4) binding, preventing viral entry[7]. Neutralizing antibodies bind the V3 loop, blocking virus attachment or fusion[8]. Allosteric inhibition by conformational change or steric hindrance.