Prostratin as a new therapeutic agent targeting HIV viral reservoirs.

The persistence of latent reservoirs of human immunodeficiency virus type 1 (HIV-1) represents a major barrier to virus eradication in patients on combination antiretroviral therapy. It has been suggested that treating infected individuals simultaneously with highly active antiretroviral therapy (HAART) and agents that activate cells to express HIV-1 might eliminate these latent reservoirs. The phorbol ester prostratin, used in Western Samoa as an ethno-botanical treatment for viral hepatitis, was isolated at the National Cancer Institute in 1992. Prostratin represents a distinct subclass of protein kinase C activators, since unlike other phorbol esters it does not induce tumor formation. Prostratin upregulates expression of viral products from latently infected cells such as U1, ACH-2 and peripheral blood mononuclear cells from patients on HAART with undetectable plasma viremia. It also inhibits HIV infection and viral spread at the entry/fusion step of viral life cycle. The lack of tumor promotion of prostratin coupled with its ability to upregulate latent HIV-1 provirus expression and inhibition of viral infection are important features that could be exploited as effective therapy to eliminate latent reservoirs.