Working model of HIV-1 entry: HIV entry is initiated by attachment of gp120 to CD4, which induces a conformational change in gp120. Following engagement of coreceptor, gp120 undergoes further conformational changes that allow for the insertion of the gp41 fusion peptide into the host membrane. The formation of the six-helix bundle brings the host and viral membranes into close proximity and creates a fusion pore, allowing entry of the HIV capsid into the host cell. | Didigu CA, Doms RW. Novel approaches to inhibit HIV entry. Viruses. 2012;4(2):309–324. doi: 10.3390/v4020309.