The overall goal of this revised competing renewal application is to study the mechanism of HIV-I replication in AM and to the mechanisms responsible for the abnormal interaction of HIV-I infected AM with uninfected cells. We will conduct these studies both in naturally infected AM from AIDS patients, and in macrophages experimentally infected in culture. In the first funding period we found that both lymphotropic and monocytotropic HIV-I strains bind, fuse, enter, and reverse transcribe viral DNA efficiently in AM, leading to our hypothesis that the basis of high level virus production and consequent cytopathology must reside in later events in replication. We have also initiated a collaboration with Dr. Gendelman to exploit his model of indirect effects of HIV-I infected macrophages in the study of lung cells. The Specific Aims of this application are: 1) To characterize the post-entry stages achieved during infection of AM and MDM by a monocytotropic and a lymphotropic HIV-I strain; 2) To elucidate the molecular basis for HIV-I tropism in AM; 3) To investigate the HIV-I env heterogeneity in viral DNA and RNA in AM and PBL from HIV-I infected persons; 4) To determine whether HIV-I infected macrophages induce cytokine production in alveolar cells. We shall employ PCR for evaluation of viral DNA and viral and cellular RNA content in clinical specimens and in cultured macrophages. We will study the migration of the viral nucleocapsid complex to the nucleus and determine the frequency of HIV-I DNA integration. We will use metabolic labeling, radioimmunoprecipitation, and cell fractionation to study the interaction of the HIV-I Env with cellular components. The cocultivation method will be used to investigate indirect effects of HIV-I infected AM on uninfected lung cells. Together these studies will define the molecular mechanisms through which HIV-I replication is controlled and itself controls AM dysfunction and thereby contributes to lung disease in AIDS.