Leukemogenic activity of thymotropic, ecotropic, and xenotropic radiation leukemia virus isolates

Abstract

Thymotropic, ecotropic, and xenotropic oncoviruses were isolated from the C57BL/6 mouse radiation leukemia system and were propagated in culture. The purified viruses were inoculated singly and in various combinations into groups of mice, and leukemia incidence was determined. Only the thymotropic virus was leukemogenic in vivo.

Frequent isolation of ecotropic murine leukemia virus after x-ray irradiation of C57BL/6 mice and establishment of producer lymphoid cell lines from radiation-induced lymphomas

“…A great deal of information is available on the radiation leukemia virus -(RadLV), an in vivopassaged murine leukemia virus (MuLV) isolated from thymic lymphomas of X-irradiated C57BL/Ka mice (17)(18)(19)24). This virus can be propagated in vitro from established cultures of RadLV-induced lymphomas and has been shown to retain its thymotropic and leukemogenic potential after reinjection into C57BL/Ka hosts (1,2,5,7,23). However, very few data exist regarding its counterpart, the wild-type RadLV, isolated directly from primary radiation-induced thymomas.…”

Azathioprine‐induced lymphocytic neoplasms of NZB mice lack ecotropic murine leukaemia virus

“…Recently recombinant viruses, some of which have characteristics common to both ecotropic and xenotropic viruses (e.g. both host ranges), have been implicated in leukaemogenesis (Hartly et al, 1977;Haas, 1978). There was no indication of such a recombinant virus in tissues from our leukaemic mice.…”

“…The reason for this precise oncospecificity of viral genomes is not known and, understandably, the lymphocytic lymphomas that can be provoked in mice by X-irradiation (Gross, 1958;Lieberman and Kaplan, 1959) or immunosuppressive drugs (Meier and Myers, 1973) have been directly or speculatively attributed to activation of their endogenous ecotropic leukaemia virus(es). More recent evidence suggests that recombinants between ecotropic and xenotiopic virus may be involved in the spontaneous development of leukaemia in AKR mice (Hartley et al, 1977), and the X-irradiation-induced RadLV system in C57BL/6 mice (Haas, 1978). A leukaemogenic recombinant virus has been isolated from stocks of Moloney murine leukaemia virus (Fischinger et al, 1975(Fischinger et al, , 1978.…”

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

“…In addition, there are envelope (env) gene recombinants between E-and X-MuLV whose host range, neutralization and interference characteristics are common to both Elder ei a/., 1977), and mink cell focus-inducing (MCF) recombinants are unique in their capacity to cause a specific type of morphological alteration in mink lung (CCL-64) cultures . Some recombinants are oncogenic and have been implicated in the pathogenesis of spontaneous and X-ray-induced leukaemia Haas, 1978).…”

“…More recently, Haas has shown that E-MuLV does appear, but transiently, in the bone marrow and thymus of C57BL/6 mice within weeks of irradiation and before they become leukaemic (Haas, 1977). Moreover, a putative, recombinant virus which is thymotropic and leukaemogenic has also been isolated from C57BL/6 thymomas maintained as cell lines in vitro (Haas, 1978). In order to clarify the situation we have X-irradiated NZB mice which do not normally harbour any detectable ecotropic MuLV and rarely develop lymphocytic leukaemia and/or thymic lymphomas spontaneously, but are distinguished by high titres of solely xenotropic MuLV.…”