Transformation by Epstein-Barr virus requires DNA sequences in the region of BamHI fragments Y and H.

Eight independent recombinant Epstein-Barr virus genomes, each of which was a transforming strain, were made by superinfecting cell lines containing Epstein-Barr virus DNA (Raji or B95-8 strain) with a nontransforming virus (P3HR1 strain). A knowledge of the constitution of each transforming recombinant allowed the localization of the defect in the genome of the nontransforming parent to a 12-megadalton sequence within the EcoRI A fragment. Within this region, the nontransforming virus has a deletion of the BamHI Y fragment and about half of the sequences in the adjacent BamHI H fragment. The present data suggest that this deletion is responsible for the nontransforming phenotype. Furthermore, mapping a deletion in one of the recombinant genomes allowed the conclusion that a sequence (comprising about 20% of the Epstein-Barr virus genome) from the center of BamHI-D to BamHI-I' is not necessary for the maintenance of transformation by Epstein-Barr virus.