Activation of Guinea Pig C-Type Virus in Cultured Spleen Cells by 5-Bromo-2′-deoxyuridine 2

Guinea pig C-type virus particles were activated by exposure of primary spleen cells of leukemic animals to a medium containing 40 µg/ml 5-bromo-2′-deoxyuridine (5-BUDR) for 48–72 houn. Abundant C-type virus particles, approximately 110 mµ, were seen in spleen cultures treated with 5-BUDR but were seldom found in parallel cultures without drug treatment. Virus particles were observed in both intracytoplasmic and extracellular spaces. Occasionally budding virus particles were found at the cell surface.