Cell surface antigen induced by avian tumor viruses in hamster cells transformed by a temperature‐sensitive mutant of rous sarcoma virus

Hamster cells (BHK21/13) transformed at the permissive temperature by a temperature‐sensitive mutant (FU 19) of the Schmidt‐Ruppin strain of Rous sarcoma virus exhibited a temperature‐dependent expression of virus‐induced surface antigen (VISA) as assayed by mixed haemadsorption test. This temperature‐dependence of VISA was not observed in cells transformed by the wild‐type virus (SR4), although the number of positive cells was reduced at the restrictive temperature (41° C) when compared to cells incubated at the permissive temperature (37° C). The relations between cell transformation and expression of VISA are discussed.