Human immunodeficiency virus type 1 envelope glycoprotein gp120 V1V2 loop (HIV-1 gp120 V1V2 loop)

The **Human immunodeficiency virus type 1 envelope glycoprotein gp120 V1V2 loop** is a highly variable region at the apex of the HIV-1 envelope trimer, spanning roughly residues 126–196 of gp120 and forming a structurally conserved beta-sheet or beta-barrel core despite extreme sequence diversity[6][9]. It plays a key role in viral fusion and entry by stabilizing the trimer structure, shielding the vulnerable coreceptor binding site, and facilitating conformational changes during receptor binding[1][2][6][5]. The V1V2 loop is a main target for broadly neutralizing antibodies and a critical determinant of immune escape; it is heavily glycosylated, which helps mask key epitopes but also creates sites of vulnerability recognized by specific antibodies such as PG9, PG16, and others[1][9][5]. Vaccine-induced responses against V1V2 correlate inversely with infection risk, highlighting its potential as a vaccine target despite high sequence and glycan variability[1]. The structure and antigenicity of this region are central to both HIV-1 pathogenesis and vaccine and antibody-based therapeutic strategies.

Other names

HIV-1 gp120 variable 1 and 2 regionHIV-1 Envelope V1/V2 loopV1V2 region of HIV-1 gp120HIV-1 Env V1V2

Neutralizing antibodies bind V1V2 and block viral entry by: - Preventing conformational changes necessary for receptor/coreceptor engagement - Inhibiting exposure of the coreceptor binding site - Disrupting stabilization of the Env trimer, leading to nonfunctional virus