ABSENCE OF ECOTROPIC OR RECOMBINANT MURINE LEUKEMIA-VIRUS IN PRELEUKEMIC AND LEUKEMIC X-IRRADIATED NZB MICE

NZB mice X‐irradiated with a single dose of 630 R when they were 1‐month old developed a high incidence of histologically defined lymphocytic leukaemia 8–25 weeks later. We have screened for murine leukaemia viruses (MuLV) in the lymphoid tissues of 8 of these leukaemic mice, and in 8 “preleukaemic”, apparently healthy NZBs, killed 1 month post irradiation. Xenotropic, but not ecotropic or recombinant MuLV, was detected by in vitro co‐cultivation of bone marrow, spleen and thymus with selectively permissive cell lines, followed by the immunofluorescence test for MuLV gs antigen, and the XC test. Our results are not consistent, therefore, with the concept that the factor causing the leukaemias was an oncogenic virus activated by X‐irradiation. Copyright © 1979 Wiley‐Liss, Inc., A Wiley Company