The major goal of this project is to determine the role of existing viruses in the etiology of AIDS. The AIDS virus, HIV, multiplies in T4 lymphocytes, kills the cells in the process, depletes the body of T4 cells and, causes an immune deficiency. HIV can also replicate in some non-T cells. For example, in most B cell lines latently infected by Epstein- Barr virus (EBV), HIV can replicate, sometimes even in a less lytic (cell killing) fashion than in T4 cells, but HIV cannot replicate in B cells without EBV. This project will study in detail the interactions between the two viruses, HIV and EBV, when both infect the same B lymphocyte. This might mimic what happens in the body and could, possibly, lead to high and prolonged production of the AIDS virus, which could eventually lead to AIDS. We are aiming to answer the following questions: 1. Why can HIV not replicate in EBV-negative B cells? 2. What does EBV contribute to these cells to enable HIV to replicate? 3. Can HIV infect non-human primate cells, immortalized by EBV? 4. What effects do drugs have on the HIV/EBV interaction? These investigations will teach us more about the biology of HIV and about situations that may occur in AIDS patients.