Combination therapy with new agents against the human immunodeficiency virus (HIV) has dramatically slowed the progression to AIDS and death. These treatments are capable of reducing virus in the peripheral blood to below the levels of detection. However, reservoirs of viral replication persist, largely in lymph node tissue, that potentially reignite HIV replication. This project examines serial samples from excisional cervical lymph node tissue and peripheral blood in patients before and during highly active therapy. It will establish a mechanism for obtaining samples from several compartments simultaneously and reproducibly. The combination of state-of-the-art flow cytometry and cell sorting, isothermal Nucleic Acid Sequence Based Assay (NASBA) HIV quantitation, and a non-radioisotope in situ hybridization technique will be used to measure cellular subtype (lymphocyte versus monocyte/macrophage) HIV viral load in these samples. Patterns of changes in cellular subcompartments across time and between the compartments will be examined in an attempt to understand treatment failure and to provide new insights into the design of more effective treatment strategies. Patients who fall into the unique category of response - coined Discordant Responders (the 15 - 20 percent of patients who experience a rise in both viral load and CD4 count in response to therapy yet appear to reap the same clinical benefits as patients with the expected virologic response), will also be studied in order to determine pathophysiologic parameters of response to therapy that go beyond absorption, adherence, and phenotypic/genotypic resistance patterns as explanations for virologic response. This project will investigate the role of viral tropism and the specific activity of treatment regimens in specific lymphoid cell subtypes, including terminally differentiated versus dividing cells. A further characterization of the subset of infected cells represents the future direction of this project, namely analysis of cell cycle by cyclins A, B and D, and will provide unique insights in how specific treatment regimens might affect total viral load. However, the paramount goal of this research career award is to provide the PI with didactic training overlapping a closely supervised period of clinical investigation leading to establishment of the PI as a viable independent researcher.