Isolation of a Murine Leukæmogenic Virus P-LLV

Abstract

THE induction of lymphocytic leukæmia and other morphologic forms of reticular neoplasms has been reported in various strains of mice by cell-free agents isolated from leukæmic tissues or from long-transplanted neoplasms of non-reticular origin^1–7. Agents producing profound hæmatopoietic disturbances have also been described^8,9. In several investigations the precise source of the virus, whether from extracted tissues or from inoculated recipient (‘activation’ of virus), has been difficult or impossible to prove^5,6. Investigations of the inter-relationships of the several viruses have been hampered because of the absence of specific virus-neutralizing antibodies in the host and the lack of rapid in vitro assays. The significance of the presence of type C particles in recipients of several of these cell-free extracts and in tissues of leukæmic mice of those high-leukæmic strains investigated¹⁰ remains to be determined.