The detection of biomarkers of oxidative stress in brain tissue and cerebrospinal fluid of patients with human immunodeficiency virus, type 1 (HIV)-associated dementia indicates the involvement of stress pathways in the neuropathogenesis of AIDS. Although the biological importance of oxidative stress on events involved in AIDS neuropathogenesis and the HIV-1 proteins responsible for oxidative stress remain to be elucidated, our results point to the activation of hypoxia-inducible factor 1 (HIF-1) upon HIV-1 infection and its elevation in brain cells of AIDS patients with dementia. HIF-1 is a transcription factor that is responsive to oxygen. Under hypoxic conditions, HIF-1α becomes stable and translocates to the nucleus where it dimerizes with aryl hydrocarbon receptor nuclear translocator and modulates gene transcription. Activation of HIF-1 can also be mediated by the HIV-1 accessory protein Vpr. In addition, cellular components, including reactive oxygen species, contribute to the induction of HIF-1α. Our results show that Vpr induces reactive oxygen species by increasing H2O2 production, which can contribute to HIF-1α accumulation. Interestingly, increased levels of HIF-1α stimulated HIV-1 gene transcription through HIF-1 association with HIV-1 long terminal repeat. These observations point to the existence of a positive feedback interplay between HIF-1α and Vpr and that, by inducing oxidative stress via activation of HIF-1, Vpr can induce HIV-1 gene expression and dysregulate multiple host cellular pathways. © 2009 by The American Society for Biochemistry and Molecular Biology, Inc.