HIV infection begins with the interaction of the HIV glycoprotein (gp) 120 with the CD4 molecule on the surface of the target cell.
Stage 1b - not yet completed (Figure 21)
Following CD4 binding, a center material change in the HIV gp 120/gp 41 complex is induced by interaction of gp 120
with the chemokine receptors CCR5 or CXCR4. This change in confirmation exposes gp 41 allowing it to initiate fusion of
the membranes. The significant role of CCR5 in this process has been revealed upon the observation that individual hemozygous for mutations within CCR5 are resistant to infection by HIV-1.
