Sequence variation of EBNA2 of Epstein-Barr virus isolates from Korea.

To reveal sequence variations in the Epstein-Barr virus nuclear antigen 2 (EBNA2) genes of Epstein-Barr virus (EBV) strains circulating in the Korean population, the EBNA2 divergent region was amplified and sequenced from 13 EBV-1 isolates, 2 EBNA2 type 1 intertypic EBV isolates, and two EBV-2 isolates, all derived from Korean cancer patients. Comparative sequence analysis revealed that type 1 and type 2 EBNA2 divergent regions of Korean EBV isolates were almost identical to the respective regions of the B95-8 EBV-1 and AG876 EBV-2 strains. Two of the nucleotide changes found in the type 1 divergent regions of all Korean isolates, G-to-T and C-to-A at B95-8 EBV positions 48,991 and 48,998, respectively, are also present in all EBV-1 strains of non-Asian origins, indicating that these two sites might be mutational hot sites. Besides these two mutations, EBV-1 strains from Papua New Guinea or European Caucasians and Africa show unique patterns of identical sequence variations from B95-8, which were not found in type 1 isolates from Korea, suggesting that Korean type 1 are evolving as a lineage distinct from isolates from Papua New Guinea or European Caucasian and Africa.