Transforming genes of chicken bursal lymphomas.

Bursal lymphomas of chickens infected with lymphoid leukosis viruses contain at least two distinct activated transforming genes: 1) a c-myc gene activated by integration of viral DNA and 2) a cellular gene, not linked to viral DNA, which efficiently induces transformation of NIH 3T3 cells. Since lymphomagenesis by lymphoid leukosis viruses appears to be a multistep process, it is possible that activation of these two different genes occurs at different stages of the disease. The bursal lymphoma transforming gene detected by transfection has been isolated by molecular cloning. Hybridization analysis indicates that this gene is homologous to normal chicken DNA sequences.