Modulation of mouse mammary tumor virus production in the MJY-alpha cell line.
Implantation of the mouse mammary tumor virus (MMTV)-producing mammary tumor cell line MJY-alpha into isogeneic mice elicited both humoral and T-cell responses against MMTV virion antigens. The carcinosarcomas which developed from the implanted cells showed a significant decrease in MMTV synthesis, compared with cells remaining in culture, which was detectable as early as 7 days after implantation and for five transplant generations. Electron microscopic examination of thin sections of the tumors revealed that intracytoplasmic A particles, budding particles, and cell-free MMTV B particles were all affected. However, immunofluorescence assays of tumor sections demonstrated the presence of MMTV viral antigens in the cells. Cell cultures initiated from first-, third-, and fourth-generation tumors were morphologically identical to the original in vitro cell line, although virus production was barely detectable. Analysis of the cultures by electron microscopy revealed a significant increase in MMTV virions after in vitro passage 3. Polypeptide profiles obtained by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of virions purified from these cultures were identical to MMTV. Immunodiffusion demonstrated the cross-reactivity between these virions and MMTV particles obtained from mouse milk. In vitro treatment of MJY-alpha cell cultures with rabbit anti-MMTV antiserum resulted in a reduction of extracellular MMTV virions, as well as alterations in their sodium dodecyl sulfate-polyacrylamide gel electrophoretic polypeptide patterns.
D000818:Animals; D000956:Antigens, Viral / Q000032:analysis; D002460:Cell Line; D005260:Female; D005455:Fluorescent Antibody Technique; D007106:Immune Sera / Q000494:pharmacology; D008325:Mammary Neoplasms, Experimental / Q000276:immunology*; D008324:Mammary Tumor Virus, Mouse / Q000254:growth & development* / Q000276:immunology; D051379:Mice; D009368:Neoplasm Transplantation; D014779:Virus Replication
D000956:Antigens, Viral; D007106:Immune Sera