[Chronic infection caused by the simian Mason-Pfizer virus in primate cell cultures]. / Izuchenie khronicheskoi infektsii, vyzvannoi obez'ian'im virusom Mézon-Pfaizera v kul'turakh kletok primatov.

Cell cultures of monkey prepuce (Rhfs) and African green monkey kidney (BSC-1) were infected once with simian Mason-Pfizer virus (MPV) and virus expression in the course of establishment of chronic infection was studied. The productive infection was characterized by changes in the cell metabolism (DNA synthesis increased 2-3-fold as early as the "zero" passage), the appearance of gs-antigen, formation of virions of type D and high activity of RNA-dependent DNA-polymerase. Multinuclear giant cells appeared only in the infected Rhfs cell culture most sensitive to MPV. In human embryo kidney culture (HEK) productive infection was also established however, HEK cultures did not survive after 3-4 passages. No signs of transformation could be found in any of the cultures studied.

Implications of humoral antibody in mice and humans to breast tumor and mouse mammary tumor virus-associated antigens.

As a part of a program directed toward the elucidation of the role of viruses in mouse and human breast cancer, a variety of immunological techniques were applied to a study of the humoral immune response of mice and of humans to their breast tumors. Tumor-bearing mice were found to produce antibodies against a complex array of tumor cell-associated antigens, including mouse mammary tumor virus (MMTV), components, heterophile and Forssman-like antigens, embryonic antigens, and possibly other tumor-associated antigens. Mice bearing MMTV-positive tumors had high titer antibodies against both viral and heterophile antigens. Tumor-free mice, whether of high or low mammary cancer strains, were remarkably free of antibodies that could label MMTV particles, although some sera contained antibodies to viral components. Patients with breast cancer also had antibodies against a variety of antigens associated with their own and homologous breast cancer cells. These antibodies reacted with heterophile, embryonic, and other tumor-associated antigens, some of which appeared to be viral. Sera of some patients with breast cancer gave positive immunofluorescence reactions with mouse mammary tumor cells grown in tissue culture and producing MMTV. Most of these reactions were due to heterophile antibodies in the sera, but a small number of sera contained antibodies apparently directed specifically toward MMTV particles, as determined by immunoperoxidase electron microscopy. Although human-mouse cross-reactions must be interpreted with caution, these data suggest that a virus putatively associated with human breast cancer is antigenically related to MMTV.

Transformation of cells in human bone tumor cultures.

Two cell lines from tumors of 16 patients with osteosarcoma and two cell lines from 5 patients with giant cell tumor of bone showed conversion of cell type after 2 to 13 months in culture. Transformed cells of epithelial like morphology appeared in small focal areas and rapidly overgrew nontransformed cells. These cells were characterized by rapid growth, loss of contact inhibition, and growth in soft agar. Attempts to demonstrate virus(es) by electron microscopy, treatment with chemicals, or by inoculation of human cell lines were thus far unsuccessful. Antigens not present in parental cultures were observed in the transformed cells by fixed immunofluorescence test with sera of 13 and 20 osteosarcoma patients and 3 of 8 patients with giant cell tumor of bone. Absorption of positive sera with transformed cells of either osteosarcoma or giant cell tumor removed the reaction but not with absorption with heterophile material or mycoplasma. Presence of group-specific-like antigen (gs-3) in the transformed cells (but not in parent cultures) was shown by immunofluorescence. Fluids of transformed cultures contained heavy RNA similar to that of oncornaviruses. These findings suggest the presence of viral information in some human bone tumors.