A murine polycythemic virus and its possible role in the study of human leukemia etiology

Abstract

A murine polycythemic virus (FV‐P) has been described that induces a rapid polycythemia in susceptible mice within three weeks postinfection. The hypervolemic polycythemia response is essentially spleen dependent. FV‐P also induces spleen focus formation on the surfaces of the spleens of infected mice nine days after I.V. inoculation of the virus. Recent studies have shown that FV‐P requires a helper virus in order to produce spleen focus formation and polycythemia. The helper virus was found to be indigenous in FV‐P preparations and is a lymphatic leukemia virus (LLV). The indigenous helper virus can be removed from FV‐P preparations and substituted by other RNA leukemic viruses from a number of species‐mice, birds, and cats. Helper activity was also found in tissue culture extracts of human leukemic spleens. Because these human extracts had the same helper activity as shown for RNA leukemic viruses from other species, there is good basis to believe that FV‐P could be useful in providing a biological assay system for the detection of a human leukemic virus.