Human immunodeficiency virus type 1 envelope glycoprotein gp120 V3 glycan-dependent epitope (HIV-1 gp120 V3 glycan epitope)

The HIV-1 gp120 V3 glycan-dependent epitope, often called the V3-glycan supersite, is a highly conserved region of vulnerability on the surface of the HIV-1 envelope glycoprotein (Env) (Sok et al., 2016, Science). This epitope is defined by a cluster of high-mannose glycans, particularly the N-linked glycan at position N332, which are anchored to the base of the V3 variable loop (Garces et al., 2015, Immunity). It serves as a primary target for potent broadly neutralizing antibodies (bNAbs) such as PGT121 and 10-1074, which are being developed for both HIV prevention and treatment (Caskey et al., 2017, Nature Medicine). Biologically, this site is part of the glycan shield that the virus uses to hide its protein surface from the host immune system, yet it remains accessible to specific antibodies that can penetrate the carbohydrate layer. In clinical applications, targeting this epitope has shown the ability to rapidly suppress viremia in infected individuals by blocking the virus's ability to fuse with host CD4+ T cells. However, the virus can escape through mutations that shift or eliminate the required glycan sites, necessitating the use of combination therapies (Schoofs et al., 2016, Science). This target is a cornerstone of current research into passive immunization and the development of immunogens for HIV vaccines.

Other names

V3-glycan supersiteN332-dependent epitopegp120 V3 loop glycan clusterMan9-rich glycan patchV3-glycan patch

Broadly neutralizing antibodies (bNAbs) target this epitope by binding to both the protein backbone of the V3 loop and the surrounding N-linked glycans, which sterically blocks the envelope trimer from interacting with the CD4 receptor and CCR5/CXCR4 co-receptors, thereby preventing viral entry into host cells (Sok et al., 2016, Science).