Activation of Rous virus in the transplanted golden hamster tumour with the aid of artificial heterokaryon formation.

Abstract

AbstractA transplanted hamster tumour induced by the Carr‐Zilber strain of Rous sarcoma virus was studied during ten consecutive passages. Mature virus, virus connected with the cells, viral antigen and antigen active in the complement fixation test were determined. The ability of Rous virus to be activated in tumour cells was also determined with the aid of heterokaryon formation with chick embryo fibroblasts.It was shown that the tumour retained in all passages the capacity for activation of Rous virus despite the disappearance of virus and viral antigen. The minimum number of cells containing one activated virus unit was increased during the tumour passages. X‐irradiation of the tumour cells did not activate the Rous virus.The method of heterokaryon formation was also successfully applied for activation of Rous virus from a cell line that had originated in a hamster Rous tumour and had been cultivated in vitro for more than two years.