Background: Elimination of the latent reservoir is crucial towards efforts to eradicate HIV. Therapeutic interventions against latent HIV have been mainly focused on ''shock and kill'' strategies. These strategies are based on the transcriptional activation of latent HIV with a Latency-Reversing Agent (LRA) with the consequent killing of the reactivated cell by either the cytopathic effect of HIV or an arm of the immune system. Several clinical trials targeting the latent reservoir with LRAs have resulted in limited to no clinical effect on the size of the latent reservoir. Some potential explanations to the failing of these strategies are: a reduced effector function of immune cells; reactivation of defective proviruses that do not produce necessary viral antigens; or a survival advantage of latently infected cells. To that end, strategies that can reactivate latent HIV and also enhance immune responses against HIV may overcome some of the disadvantages of current cure efforts.
Methods: We have developed a primary cell model to identify cytotoxic enhancing agents (CEAs) that will enhance the killing capacity of CD8T cells. This method relies on a mix-lymphocyte reaction (MLR) in which polyclonally activated CD8T cells are co-cultured with allogeneic polyclonally activated CD4T cells from a different donor. CD4T cells are activated in conditions to generate central memory CD4T cells (T_CM) cells, as this cell subset is the major contributor to the latent reservoir and is more resistant to apoptosis than other subsets of CD4T cells. Cell death in both CD4 and CD8 subsets is measured by flow cytometry.
Results: We have characterized two potential CEAs. The first one is the LRA HODHBt, a STAT SUMOylation inhibitor. HODHBt enhances the cytotoxic capacity of CD8T cells by increasing their cytolytic potential. The second one, ABT-199, is a Bcl-2 inhibitor that increases the sensitivity of CD4T cells to the killing machinery of CD8T cells.
Conclusions: We have developed a reliable primary cell paradigm to study and screen strategies that will enhance the cytotoxic capacity of CD8T cells. This new primary cell model will help in the development of effective ''shock and kill'' strategies to reduce or eliminate the latent reservoir.

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