Highly purified CD25(-) resting T cells cannot be infected de novo with HIV-1

Previous studies have demonstrated that the expression of CD25 can distinguish CD25(-) latently infected cells from CD25(+) cells actively producing virus. Our studies were designed to characterize the nature and stability of the viral genome in CD25(-) quiescent HIV-1-infected cells and to determine whether these cells could be infected de novo with HIV-1. Our results show that: (i) When unfractionated peripheral blood mononuclear cells are first infected with HIV-1 and the CD25(-) cells then isolated, the latter contain only incomplete DNA transcripts and no full-length DNA or 2-LTR circles, Phytohemagglutinin activation of these CD25(-) cells results in the generation of full-length viral DNA and p24 production, (ii) When CD25(-) CD4(+) cells are first purified from peripheral blood mononuclear cells and then incubated with HIV-1, viral DNA cannot be detected, suggesting that these purified cells cannot be infected, Furthermore, CD25(-) adherent cells do not facilitate the infection of CD4(+) CD25(-) cells when they were present at the time of incubation with HIV-1, Taken together, these studies suggest either that (i) the CD25(-) cells containing incomplete DNA transcripts are derived from infected-activated CD25(+) cells, which subsequently become CD25(-) or (ii) the presence of CD25(+) cells is required for the infection of CD25(-) cells in vitro.