Invstigation of the presence of viral particles in Rous virus transformed hamster cell lines

Abstract

AbstractIn the framework of a study on the recovery of the Rous Sarcoma Virus (RSV) from transformed mammalian cells, nine Syrian hamster cell‐lines transformed by RSV were examined by electron microscopy. Six of these lines were obtained from BHK 21/Clone 13 cells transformed in vitro by RSV, either Schmidt‐Ruppin strain (SR‐RSV) or Bryan strain (B‐RSV), one of them being supertransformed by polyoma virus. Another line (RSH) was obtained from embryonic hamster cells transformed in vitro by SR‐RSV. Two lines resulted from in vivo experiments: SR/Cl2 was obtained from a SR‐RSV‐induced tumour in a Syrian hamster; and RS2‐TH2 represented an in vitro cultured tumour obtained in a Syrian hamster by the inoculation of RS2 cells transformed in vitro by SR‐RSV. All these lines had the group‐specific antigen (GS) and it was possible to rescue RSV from all lines except SR/Cl2 when they were cultivated in association with permissive chick cells.No C‐type virus particles could be observed either in the six lines transformed in vitro or in two lines (RSH and SR/Cl2) transformed in vitro. On the contrary, the line RS2‐TH2 contained C‐type particles, morphologically similar to murine leukemia virus, and probably representing a latent hamster virus. In line SR/Cl2, A‐type particles were found associated with mitochondria. The significance of the presence of these particles in this only non‐virogenic line is discussed. Finally, in all the hamster lines examined, R‐type particles were observed. They were more numerous in the in vivo transformed lines than in the in vitro transformed lines.