ELECTRON-MICROSCOPIC DEMONSTRATION OF VIRUS-PARTICLES IN ACUTE LYMPHOBLASTIC-LEUKEMIA IN SPRAGUE-DAWLEY RATS

Retrovirus-like particles were detected by the negative staining metho d in supernatants of lymph node and spleen cell suspensions prepared f rom Sprague-Dawley rats with spontaneous acute lymphoblastic leukaemia (ALL). Similar particles were found in supernatants of cell suspensio ns from a lymphoma that developed after inoculation of lymph node and spleen cell suspension prepared from animals with spontaneous ALL into the subcutis of Sprague-Dawley recipients. On ultrathin sections, bud ding forms of the virus particles were seen as a dot at the periphery of neoplastically trasformed cells.