Characteristics of Long-Term Marmoset Cell Cultures Spontaneously Altered or Transformed by Rous Sarcoma Virus2

Abstract

Cells from a kidney obtained by unilateral nephrectomy of an adult male marmoset (Saguinus fuscicollis) were established in cell culture and exposed to Schmidt-Ruppin Rous sarcoma virus (SR-RSV) at various passage levels. In 5 independent experimental series, only 1 culture of 6 inoculated cell lines was transformed by SR-RSV when the cells were inoculated in the G₁ phase. The transformed cells formed foci of sarcoma cells in culture vessels, retained a normal diploid chromosome complement, grew in soft agar, and produced a tumor after transplantation into the original kidney-donor animal. The same cells, however, did not grow as microtumors after implantation into hamster cheek pouches. No infectious virus could be recovered from the cells transformed in vitro even after cocultivation with chick embryo fibroblasts, but infectious SR-RSV was recovered by the same technique after the cells had grown as a sarcoma in the autologous animal. Of 7 uninoculated cell lines and 5 lines inoculated with SR-RSV but not transformed, 5 permanent cell strains were established. All 5 cell strains have been maintained in vitro for about 4 years. The emergence of permanent cell strains was or was not accompanied by morphological and/or chromosomal alterations. The chromosomal changes consisted of a reduced number of diploid cells with concomitant appearance of bizarre chromosomes such as dicentrics, rings, or extra large chromosomes. None of the spontaneously altered or unaltered cells grew in soft agar nor did they induce tumors on transplantation into the original kidney donor or into hamster cheek pouches. These observations are important in the current consideration of the use of cell culture lines or strains for the production of viral vaccines.