Silencing of HALP Decreases HIV-1 Infection of Primary CD4+ T-cells (45.4)

Abstract

Abstract HIV/AIDS is an ideal candidate for a novel gene therapy approach since it is an incurable and terminal disease. We have identified a set of candidate host cell genes, associated with survival of HIV-infected T-cells. We named one of these genes, “HALP”, for “HIV-Associated Life Preserver”. Recently, we used a lentiviral vector to stably express HALP shRNA in primary human CD4 T-cells. In the absence of HIV infection, silencing of HALP appeared to have no effect on viability of these cells. As predicted, silencing of HALP markedly reduced HIV infection of primary CD4+ T-cells, as measured by the percent of p24+ cells and by supernatant p24. Published data suggest that hypoxia induces HALP expression by increasing the activity of the transcription factor, Hif-1α. HIF-1 binding sites have been identified within the HALP promoter and HALP is responsive to HIF-1 in non-immune cells. We show here that HIV-1 infection of primary CD4+ T-cells increases Hif-1α mRNA expression, as measured by real time RT-PCR. Transfection of T-cells with wild-type Hif-1α or with a mutated form of Hif that is resistant to proteolysis (Hif-DPA) also increased expression of HALP mRNA. These data are consistent with a pathway of Hif-induced HALP expression in HIV-1 infected cells, leading to a hypoxia-like stress response and, ultimately, to cell survival. Our work represents one of the first attempts to search for novel cellular genes that contribute to viral inhibition of host cell apoptosis and, thus, to viral latency. HALP represents a candidate for a host cell anti-apoptotic protein, which is triggered by HIV infection, and may provide a novel molecular target for drug use and design.