Tumor induction by direct injection of cloned v-src DNA into chickens

The in vitro transforming potential of Rous sarcoma viruses has been shown to reside in a gene segment, v-src. To provide direct proof that the isolated v-src sequence contains all the information necessary for sarcoma induction in vivo, we have injected subgenomic and genomic cloned DNA carrying v-src directly into chickens. We report that v-src, without the complements of other viral genes, can effectively induce sarcomas in the host within weeks after injection. The sarcoma tumors generated by subgenomic v-src DNA are of mono- or oligoclonal origin. They have acquired v-src sequences in the genome and expressed high levels of src messages. Intact long terminal repeats do not seem to be essential in the tumorigenic process.