Unité génétique moléculaire des Bunyaviridés, Laboratoire de pathogénie virale moléculaire, Inserm U819, Institut Pasteur, 25, rue du Docteur-Roux, 75724 Paris
The strategy used by HIV to enter target cells is unique among enveloped viruses, and involves a series of complex molecular interactions between the surface subunit of the envelope glycoprotein (gp120) and at least two specific receptors : CD4 and one of the chemokine receptor CCR5 or CXCR4. The current model of HIV entry proposes that conformational changes in gp120 induced by binding to CD4 expose a cryptic domain of gp120 that is capable of interacting with CCR5 or CXCR4 present at the surface of target cells. The contact between HIV and its second receptor (or co-receptor) induces a new conformational change in the envelope glycoprotein, this time involving the transmembrane subunit gp41. This stage initiates the process of membrane fusion necessary for the penetration of the viral replicative machinery into the cytoplasm.