CD4 and HIV-1 infection: Upon challenge with HIV-1JRFL, mice reconstituted with untransduced PBMCs had an acute, progressive HIV-1 infection with high viral loads, massive CD4+ T-cell depletion and profound immunodeficiency that occurred within 2 weeks.130,131 Despite this acute, rapidly progressive and aggressive infection, pVL in the mice transplanted with PBMC expressing shPromA was significantly lower than in mice treated with the control mutated shPromA-M2 construct, which does not efficiently suppress the virus in vitro.