The purpose of this project is to determine humoral and cell- mediated immunity to EBV-associated antigens in normal individuals and patients with infectious mononucleosis and cancer in order to determine the role of EBV in human malignancy. Serologic tests measuring antibody to the EBV viral capsid antigen, early antigens, complement fixing antigen, and nuclear antigen are compared with results of skin tests and in vitro assays of cellular immunity to virus and tumor-associated antigens. Major emphasis is placed on studying American patients with Burkitt's lymphoma (obtained via the American Burkitt Lymphoma Registry), patients with Hodgkin's disease and families where many first degree relatives have cancer. Immune response to EBV in non-human primates inoculated with viral reagents are used to determine factors controlling EBV oncogenicity.