This summer I am working through the Undergraduate Fellowship Program at the Tulane National Primate Research Center in the division of Regenerative Medicine under Dr. Stephen Braun. As a model of HIV latency, we are studying the effects of the HIV transcription factors Tat (transactivator of transcription), LAP (liver-enriched activator protein), and LIP (live-enriched inhibitory protein) on HIV LTR promoter activity in U937-VRX494 cells in vitro. U937-VRX494 cells are cells of myeloid lineage that secrete a large number of chemokines and cytokines. They contain an HIV based vector (VRX494) with the Green Fluorescent Protein (GFP) marker gene by the HIV LTR. We are transfecting them with various concentrations and combinations of the different HIV transcription factors (Tat, LIP, and LAP) and observing the GFP expression, quantitatively measured by flow cytometry. We expect to find potential interactions of host transcription factors on HIV LTR activity during HIV latency.