CCR5 and HIV-1 infection: It is well known that HIV-1 infections involve binding of the viral external envelope glycoprotein (gp120) to cell-surface cluster of differentiation 4 (CD4) molecules, followed by interactions with coreceptors of C-X-C chemokine receptor type 4 (CXCR4) and C-C chemokine receptor type 5 (CCR5; T cells and macrophage cell-surface binding of the natural chemokine receptors), which results in the fusion of the viral and cellular membranes [9].