Human immunodeficiency virus type 1 envelope glycoprotein trimer V1V2 apex epitope (HIV-1 Env V1V2 apex)

The HIV-1 Envelope (Env) trimer is the sole viral protein on the surface of the virus responsible for mediating entry into host cells (PubMed: 24171834). The V1V2 apex epitope is a quaternary structure located at the top of the Env spike, formed by the association of three gp120 subunits (UniProt: P04578). This region is characterized by a high degree of glycosylation and structural variability, yet it contains conserved elements critical for the stability of the trimer in its pre-fusion closed conformation (PubMed: 21903993). Broadly neutralizing antibodies (bNAbs) that target this apex, such as PG9, PGT145, and CAP256-VRC26.25, are of significant therapeutic interest because they can neutralize a wide range of HIV-1 global isolates (PubMed: 25428514). By binding to these epitopes, these agents prevent the virus from undergoing the conformational changes necessary for CD4 receptor binding and subsequent membrane fusion (PubMed: 24670665). Research into this target is central to both passive immunization strategies and the design of structure-based vaccines aimed at eliciting similar protective antibody responses (PubMed: 30212447).

Other names

HIV-1 Env trimer apexV1V2 quaternary epitopegp120 V1V2 loopApex of the HIV-1 envelope spike

Broadly neutralizing antibodies bind to the quaternary V1V2 apex of the HIV-1 Env trimer, stabilizing the pre-fusion state and sterically hindering the conformational changes required for CD4 binding and subsequent viral-host membrane fusion (PubMed: 24670665).