A novel in vitro system to generate and study latently HIV-infected long-lived normal CD4+ T-lymphocytes

Studies of mechanisms of HIV-latency and its reactivation in long-lived resting CD4+ T-lymphocytes in patients have been limited due to the very low frequency of these cells ( approximately 1-10 cells per 10(6) CD4+ T-cells). To circumvent this obstacle, an in vitro culture system for post-activation long-term survival of normal CD4+ T-cells in a quiescent (non-cycling) state was developed and used to generate latently infected, long-lived quiescent CD4+ T-cells from HIV-infected, activated normal CD4+ T-lymphocytes. This yielded a frequency of approximately 5x10(4) latently infected cells per 10(6) cells in culture, which is approximately 10(3)- to 10(4)-fold higher than that available from patients. Moreover, 5-10% of long-term surviving non-cycling T-cells were found to make infectious HIV continuously at low levels, showing that HIV production from infected T-cells does not require full cellular activation. This model system should facilitate studies of long-lived, latently infected and persistently HIV-producing quiescent normal CD4+ T-lymphocytes.