Absence of ecotropic or recombinant murine leukaemia virus in preleukaemic and leukaemic X‐irradiated NZB mice

Abstract

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.

Expression of an endogenous retroviral transcript is associated with murine lupus

“…Previous attempts to isolate infectious MCF virus from NZB mice have been unsuccessful (ref. 30 and Pincus T: personal communication, and Kozak C: personal communication). Although the LTRs of endogenous MCF RNAs are distinct from those of known infectious MCF viruses because of a 190-bp insert (7), whether endogenous 8.4-kb MCF transcripts encode an infectious virus(es) remains to be determined.…”

Absence of Activated Murine Leukaemia Virus in X-irradiated CBA/H-T6Crc Mice

“…Furthermore, cell lines derived from C57B1/6 thymic lymphomas may harbour, in addition to non-leukaemogenic ecotropic and xenotropic MuLV, thymotropic virus that is highly leukaemogenic and which is thought to be a recombinant of ecotropic and xenotropic MuLV (Haas, 1978: Lieberman et al, 1979. However, studies of radiation-induced leukaemia in other strains of mice (Arnstein et al, 1976;Ihle, 1977;Harvey et al, 1979;Ellis et al, 1980) have failed to show a simple relationship between MuLV expression and leukaemogenesis, although few of the studies examined pre-leukaemic tissues and all were complicated by the presence of xenotropic MuLV. In view of these discordant results, we have attempted to clarify the situation by examining radiation leukaemogenesis in CBA/H-T6Crc mice, a substrain that does not normally express any infectious MuLV and from which virus is not readily activated using halogenated pyrimidines (M. Haas, personal communication), even though molecular hybridization has demonstrated the presence of multiple copies of the viral genome (N. Teich, personal communication).…”

Time course of C‐type retrovirus expression in mice submitted to osteosarcomagenic doses of 224radium

“…It has been proposed that endogenous murine Ctype viruses play a role in the pathogenesis of radiation-induced leukemia in mice (Kaplan, 1977). More recently, however, this concept was challenged by several groups on the basis of new biochemical, serological and virological evidence (Ihle et a1.,1976a, b ;Nagao, 1977;Harvey et al, 1979). It was thus of interest to investigate whether C-type retroviruses are associated with radiation-induced malignancies other than lymphomas in mice.…”