Chicken Sarcomas and Expression of Chicken Endogenous Virus after Transplantation of Virus-Free Rous Hamster Tumor Cells

SummaryInoculation of B-RSV(-) avian sarcoma virus transformed, but infectious virus-free hamster tumor cells into diverse strains of chicks resulted in the induction of sarcomas at the site of inoculation in the inoculated chicks. The induced sarcoma cells were of chicken karyotype. They contained high titers of the group specific (gs) antigens of the viruses of the avian leukosis-sarcoma virus group. Sarcomas induced in chicks with no demonstrable avian leukosis gs antigen or rescuable chicken endogenous virus (chick helper factor) contained no demonstrable infectious virus, whereas, those induced in genetic lines of chickens which express the chicken endogenous type C RNA virus either as infectious virus or as rescuable chick helper factor contained the chicken endogenous virus pseudotype of the defective avian sarcoma virus (Bryan Rous sarcoma virus). Our studies suggested that B-RSV(-) viral gene sequences responsible for the sarcomagenic transformation of the chick cells and gag gene sequences respo...