Characteristics of and relationship between C particles and intracisternal A particles in cloned cell strains.

Four murine tissue culture cell strains, which originated by cloning from one common cell of subcutaneous connective tissue origin, were examined for the presence of virus by electron microscopy and complement fixation techniques. The relative distribution of C particles and intracisternal A particles was determined. Thereafter, the characteristics of and relationship between A- and C-type particles were investigated.

Search for "indicators" of neoplastic conversion in vitro.

Certain responses of mouse and hamster cells to polyoma virus were examined with respect to their specificity as "indicators" of neoplastic conversion in vitro. These responses included the development of transplantation antigens and changes in morphologic growth pattern, cytology, karyology, rates of proliferation, and glycolytic activities. Under limited conditions, i.

Neoplastic transformation of mouse and hamster cells in vitro with and without polyoma virus.

Several cell lines were examined under different culture conditions in an effort to find one that would not undergo "spontaneous" neoplastic transformation but could be transformed by polyoma virus. With such a cell line, large numbers of neoplastic and non-neoplastic cultures might be obtained for comparative studies. Four cell lines derived from different tissues of 2 strains of mice and all 8 lines of cells from 5 different pools of hamster embryo cells underwent spontaneous neoplastic transformation without polyoma virus.

Virus particles and murine leukemia virus complement-fixing antigen in neoplastic and nonneoplastic cell lines.

Twenty-seven lines of murine tissue cultures derived from 12 different cell pools and grown on various media were examined with the electron microscope for morphologically detectable virus particles. They were also tested for complement-fixing mouse leukemia virus antigens and for recoverable virus. A 100-percent correlation between results obtained by these two methods is reported.