Human immunodeficiency virus type 1 envelope glycoprotein gp120 co-receptor binding site (HIV-1 gp120 CoRBS)

The HIV-1 gp120 co-receptor binding site (CoRBS), which includes the m36 epitope, is a highly conserved functional domain on the surface of the HIV-1 envelope glycoprotein (Env) (Kwong et al., 1998). This region is essential for viral entry as it mediates the interaction with host co-receptors CCR5 or CXCR4 after the virus has initially attached to the CD4 receptor (Chen et al., 2008). The site is typically hidden or masked in the native trimeric state of the envelope protein and only becomes fully exposed through a conformational change induced by CD4 binding, leading to the formation of the bridging sheet (Rizzuto et al., 1998). Due to its vital role in the viral life cycle and its high degree of conservation across different HIV-1 strains, this region is a major focus for the development of entry inhibitors and neutralizing antibodies (Zhang et al., 2010). The m36 epitope specifically refers to the binding site of the m36 human domain antibody, which is a potent inhibitor capable of neutralizing a broad range of HIV-1 isolates by blocking co-receptor engagement (Chen et al., 2008). Therapeutic strategies targeting this region aim to prevent the fusion of the viral and host cell membranes, thereby halting the infection process (Dimitrov, 2009). Because the epitope is recessed and transiently exposed, small-format antibodies like m36 are particularly effective at reaching the target compared to bulkier traditional antibodies (Zhang et al., 2010). This target represents a significant opportunity for broad-spectrum HIV-1 therapy due to the functional necessity of the co-receptor interaction (Chen et al., 2008).

Other names

CD4-induced epitopeCD4i epitopem36 epitopegp120 bridging sheetCo-receptor interaction regionHIV-1 gp120 CoRBS

Inhibition of viral entry by sterically blocking the interaction between the gp120 glycoprotein and host co-receptors (CCR5 or CXCR4).