ROLE OF REPLACED V-SRC AND ENV GENES IN THE DUCK-ADAPTED VARIANT OF ROUS-SARCOMA VIRUS

The env and v-src genes of a duck-adapted variant of Rous sarcoma viru s were replaced for corresponding genes from parental chick-derived vi rus. The generation of viral constructs with replaced genes is describ ed. DNAs of viruses with replaced genes were assayed on chick and duck embryo fibroblasts by transfection assays. Transformation efficiency was measured by the focus assay and multiplication of virus by the rev erse transcriptase assay. Duck-adapted virus with replaced env gene lo st the higher transformation efficiency for duck cells, whereas replac ement of the v-src gene had no effect on its host-specific transformat ion activity.