Objectives: 1. To study biological properties of human herpeviruses and human papovaviruses tentatively associated with tumors in human patients. 2. To study lymphocyte blastogenic response of human patients to viral antigens (herpes simplex and papovaviruses). Major findings: 1. Rapid flow microfluorometer measurement of the cell DNA content has been applied to determine lymphocyte blastogenic response to PHA and a specific antigen (PPD). Work is now in progress to apply this assay to evaluate blastogenic response of human peripheral blood lymphocytes to viral antigens. 2. Two of eleven Syrian hamsters inoculated by intracerebral route with M.M. virus (a human papovavirus isolated from the brain of a patient with Wiscott-Aldrich syndrome) have developed intracranial tumors 6 months post-injection. 3. Studies are in progress to elucidate the possible biological significance of a receptor-site for the Fc fragment of immunoglobulin that appears in herpes simplex infected cells. It has been found that engagement of the Fc site significantly decreases the total yield of virus from infected cells. Proposed course: 1. Preparations of herpesvirus virions (capsids versus enveloped virus) are being purified in order to be tested on antigens in a lymphocyte transformation assay. 2. Experiments are in progress to test the oncogenic potential of M.M. virus in newborn hamsters using the intravenous route for inoculation of the agent. 3. Attempts to establish cell lines from a variety of human brain tumors obtained at surgery will continue. These lines may provide a suitable approach for evaluating the role of human papovaviruses in CNS neoplasms.