Thus, the significance of the thiol/disulfide exchange in the process of HIV-1 infection has been established predominantly using CD4/coreceptor-positive cell lines and laboratory-adapted, CXCR4-tropic (X4) HIV-1 strains, with a limited number of studies employing primary human cells and/or R5-tropic (R5) HIV-1 isolates[16,19,22,25,26]. This evidence concerns the gene CD4 and HIV-1 infection.