Mapping of putative transforming sequences of EBV DNA.
The linkage of restriction enzyme fragments of DNA of the B95-8 strain of Epstein-Barr virus has been determined. Two approaches are being employed to define which EBV DNA sequences are needed to initiate and maintain the transformation of lymphocytes to lymphoblasts capable of long-term growth in culture. The first approach is to determine the differences between the DNA of strains of EBV which possess transforming capacity and the DNA of the HR-1 strain which cannot transform. The data indicate that EBV (HR-1) DNA lacks approximately 2--3 x 10(6) daltons of DNA contained largely in the HsuI B and EcoRI (J-K) and A fragments of EBV (B95-8) DNA and in the EcoRI A and HsuI B fragment of the W91 strain. The DNA common to HsuI B and EcoRI A fragments lies between 27 and 42 x 10(6) daltons from the HsuI A end of the molecule. This finding is compatible with the hypothesis that the inability of the HR-1 strain to transform is due to the absence of DNA needed for transformation. The second approach is to identify and map the DNA encoding polyadenylated viral RNA in cultures of restringently infected cells which contain the EBNA antigen and show no evidence of abortive or productive infection. Previous data indicated that viral RNA species encoded by 5% of the viral DNA are adenylated and identified in the polyribosomes of restringently infected cells. The data indicate that these RNAs are encoded primarily by the HsuI A (and to a lesser extent, B) fragment of EBV (B95-8) DNA. This would place the DNA encoding the viral RNA processed in restrigently infected cells adjacent to and possibly overlapping the small DNA segment deleted from the DNA of the non-transforming HR-1 strain.