CCR5 and HIV-1 infection: It has been documented that homozygous carriers of Δ32 mutation are largely resistant to R5 tropic HIV-1 infection that is exclusively detected in the transmitted founder viruses during the acute infection because the mutation prevents functional expression of CCR5, a coreceptor used by HIV-1 to enter immune cells (Cocchi et al., 1995; Samson et al., 1996; Biti et al., 1997).