A variety of agents demonstrate potent anti-HIV and immunomodulating activities in vitro, but produce minimal efficacy and severe toxicity in AIDS patients. We propose to use liposomes to selectively target anti-retroviral agents to cellular sites of HIV infection, and immunomodulatory agents to specific immune effecter cells. Site-specific delivery should enhance antiviral activity and the host-immune anti-HIV response, while reducing toxicity. We will selectively target liposomes to T4 lymphocytes and PBM, the primary cellular targets for HIV, and essential components of the cellular immune response. We will maximize liposome specificity for both the uninfected cells, and these cell s when infected with HIV- 1. We will then investigate the effects of these liposomes on the antiviral effects of a variety of anti-HIV agent and the immunomodulatory activity of several cytokines. Agents which specifically block HIV replication: oligodeoxynucleotides (ODN) anti-sense to critical HIV-mRNA sequences, and trans-dominant mutants HIV-REV proteins, will be preferentially targeted to their appropriate intracellular sites of action by liposomes. These studies will proceed in 3 phases: 1) targeting liposomes to uninfected, or to HIV-infected lymphocytes and PBM in vitro by optimizing liposome size, surface charge, and lipid composition. We will further enhance delivery by conjugating these liposomes to MAb directed against CD4 and/or gpl2O, or to rCD4. 2) We will assess in vitro the abilities of these free and liposome-encapsulated anti-HIV agents to inhibit HIV production in infected cells, and to prevent transmission to uninfected CD4+ cells. 3) In mice, we will compare the tissue distribution, target cell localization, immunomodulation, and toxicity of anti-retroviral agents and immunomodulators after administration free or in liposomes. We will test liposomes containing A) DOTMA, which fuse with cell and nuclear membranes, and are avidly taken up by human lymphocytes and PBM, B) cardiolipin, which produces direct anti-HIV activity in vitro, and, C) gangliosides, which increase liposome circulation times. We will then conjugate these liposomes to an anti-mouse CD4 MAb , and/or to a mouse pan T cell MAb, to further enhance in vivo targeting. In conclusion, we will develop liposome formulations which maximize the activity of anti-HIV and immunomodulating agents in vitro. We will then optimize their uptake in circulating T lymphocytes, lymphoid tissues, PBM/macrophages, and the CNS in normal mice, while assessing their immunomodulatory and toxic effects. This approach may substantially improve the therapeutic index of both existing anti-AIDS therapies, as well as those now being developed.