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 (∼ 1-10 cells per 10⁶ 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 ∼ 5 × 10⁴ latently infected cells per 10⁶ cells in culture, which is ∼ 10³- to 10⁴-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.