In-vitro HIV-1 infection of PBMC with NL4.3, a CXCR4-using HIV-1 variant, and NL4.3-BaL, a CCR5-using HIV-1 variant, showed no differences in p24 production indicating that PBMC from donors carrying a minor allele of rs4131564 in FUT8 and donors homozygous for the major allele were equally susceptible to HIV-1 replication (Fig. 4a). This evidence concerns the gene CXCR4 and HIV-1 infection.