The acquired immune deficiency syndrome (AIDS) is a disease of unknown etiology which causes progressive loss of immune function and multiple serious infections in male homosexuals, intravenous drug abusers, Haitians, hemophiliacs, female consorts of men in the high risk groups and infants having close contact with patients or other individuals in the high risk groups. Kaposi's sarcoma occurs in its highly malignant form in 30-40% of AIDS patients. It is not clear whether one agent or several agents acting in concert are responsible for precipitating the disease. We will identify and characterize viral agents associated with AIDS and Kaposi's sarcoma using a variety of microbiological, serological and molecular virological techniques. We plan: i) to conduct thorough diagnostic virology studies on AIDS patients, especially children, in an attempt to isolate viruses from hematopoietic elements and other affected tissues; ii) to establish cell lines from tissues of AIDS patients and to examine these for cell origin, presence of viruses, viral nucleic acids, or viral-specific antigens; iii) to transmit AIDS agents in vitro to primary and continuous hematopoietic cell lines of man and subhuman primates; and iv) to determine whether cytomegalovirus alone or in combination with other viruses isolated from AIDS patients will transform morphologically human endothelial cells or monocyte cultures in vitro.