Initial HIV-1 infections of SCID-hu Thy/Liv animals resulted in a near-eradication of CD4+/CD8+ DP thymocytes and a decrease in the CD4+ SP T cell population of the human implanted tissue [77,87,88], a depletion shown to be reduced upon treatment with several anti-HIV compounds [89-93] (Table 3). This evidence concerns the gene CD4 and HIV-1 infection.