Tissue distribution of radiation leukemia virus (RadLV) was examined after its inoculation into normal C57BL/6J (B6) mice, B6 mice bearing a transplantable, non-virus-producing thymic
lymphoma (RL12-NP), and B6 mice bearing a transplanted non-virus producing, Harvey murine sarcoma virus-transformed
fibrosarcoma. Virus expression was determined by competition radioimmunoassay for murine leukemia virus (MuLV) p30 (predominant group-reactive
antigen of MuLV) and for RadLV p12 (a highly type-specific MuLV
polypeptide) and by membrane immunofluorescence for cell surface gp71 (predominant envelope
glycoprotein of MuLV). Normal adult B6 mice were given three sequential iv
injections of RadLV and were examined several times up to 200 days later for the appearance of neoplastic disease or expression of virion
antigens. No clinical abnormalities were noted, and animals remained healthy for greater than 200 days. Significant levels of MuLV p30 and RadLV p12 were detected only in the thymuses. Organs and
tumors from RL12-NP-inoculated animals contained low or nondetectable levels of virion
antigens. Inoculation of mice with RL12-Rad, a cell line derived by in vitro
infection of RL12-NP cells with RadLV, produced widespread, discrete metastatic
tumors and infiltrated the lymphoid organs of B6 mice in a pattern identical to that observed after administration of RL12-NP cells. Lymphoid organs of RL12-Rad-inoculated animals expressed variable levels of virion
antigens reflecting differences in the extent of
tumor cell infiltration as opposed to virus spread from
tumor to host cells. Administration of infectious RadLV systemically into RL12-NP
tumor-bearing animals converted these
tumors to
viron antigen expressors with levels in superinfected
tumors equivalent to those found in RL12-Rad-induced
tumors.
Infection was highly selective, and host tissues were minimally contaminated by the inoculated virus. Part of this selectivity was explained by the thymotropic property of RadLV. A rapidly dividing murine
fibrosarcoma was not infected by RadLV, but this same non-virus-expressing
tumor could be infected by common fibrotropic MuLV isolates.