Elimination of HIV-1 latently infected cells using the cytopathic properties of Vpr.

Jana Blackett, Eric Verdin and Vicente Planelles. Department of Pathology University of Utah School of Medicine (USA).

Background: HAART frequently leads to suppression of viral replication to levels that are below detection.  However, the persistence of latently infected cells can always be demonstrated.  We have explored a potential treament that would activate latently infected cells and induce virus production, followed by a treatment that would promote apoptosis in these cells.  We hypothesize that the onset of early apoptosis will interfere with the ability of the infected cells to produce infectious virus and will therefore hinder spread.  We recently identified the ATR pathway as a major mediator of cell cycle arrest (Roshal, J. Biol. Chem, In Press) and apoptosis (unpublished) by HIV-1 vpr .  Thus, we set out to test the effects of lymphocyte activation in conjunction with activation of the ATR pathway on production of infectious virus by latently infected cells. Material and Methods: We have used a recently described model of HIV-1 latency (Jordan, EMBO 22:1868, 2003).  Latently infected CD4+ lymphocytes were treated with activating agents (TNF-alpha or TPA) for 2 to 7 hours, followed by treatment with genotoxic agents that are known to activate the ATR pathway (hydroxyurea or doxorubicin). Results: Initial results demonstrated that apoptosis inducers that act throught the ATR pathway are extremely effective at preventing the production of infectious virus from latently infected cells.  We tested a variety of in vitro regimens in which the relative concentrations and timings of lymphocyte activators and genotoxic agents were varied.  We found specific sequential treatments that led to death and little or no production of infectious virus by latently infected cells, in the face of lymphocyte activation. Conclusion: Our preliminary results demonstrate the feasibility of inducing premature death of latently infected lymphocytes following T-cell activation, using an in vitro model. Further experimentation will attempt to define whether this strategy or variations thereof would be suitable for clinical application.