Objective:

To determine whether latency can be established and reversed in both proliferating and nonproliferating CD4+ T cells in the same model in vitro.

Methods:

Activated CD4+ T cells were infected with either a nonreplication competent, luciferase reporter virus or wild-type full-length enhanced green fluorescent protein (EGFP) reporter virus and cultured for 12 days. The cells were then sorted by flow cytometry to obtain two distinct T-cell populations that did not express the T-cell activation markers, CD69, CD25 and human leukocyte antigen (HLA)-DR: CD69− CD25− HLA-DR− small cells (nonblasts) that had not proliferated in vitro following mitogen stimulation and CD69− CD25− HLA-DR− large cells (which we here call transitional blasts) that had proliferated. The cells were then reactivated with latency-reversing agents and either luciferase or EGFP quantified.

Results:

Inducible luciferase expression, consistent with latent infection, was observed in nonblasts and transitional blasts following stimulation with either phorbol-myristate-acetate/phytohemagglutinin (3.8±1 and 2.9±0.5 fold above dimethyl sulfoxide, respectively) or romidepsin (2.1±0.6 and 1.8±0.2 fold above dimethyl sulfoxide, respectively). Constitutive expression of luciferase was higher in transitional blasts compared with nonblasts. Using wild-type full-length EGFP reporter virus, inducible virus was observed in nonblasts but not in transitional blasts. No significant difference was observed in the response to latency-reversing agents in either nonblasts or transitional blasts.

Conclusion:

HIV latency can be established in vitro in resting T cells that have not proliferated (nonblasts) and blasts that have proliferated (transitional blasts). This model could potentially be used to assess new strategies to eliminate latency.

Background

Despite the successes of antiretroviral therapy (ART), HIV cannot be cured because of the persistence of latently infected resting and proliferating memory T cells [1–5]. One strategy being developed to eliminate latently infected T cells is to stimulate HIV transcription using latency-reversing agents (LRAs)[6]. The response to LRA stimulation has recently been shown to depend on the viral integration site [7], however other factors such as the proliferative history and cellular activation state may also play a role.