Strain variation in Epstein-Barr virus immediate early genes.

RNase protection analysis of mRNAs for Epstein-Barr virus (EBV) genes activated early in the induction of the productive cycle in Akata cells has confirmed that BZLF1 and BRLF1 behave as immediate early genes. These are likely to be the only virus immediate early genes since analysis of three other transcripts previously suggested to behave as immediate early genes in this system shows that they are, in fact, early genes. Western blotting of BRLF1 and BZLF1 demonstrates expression of these proteins early in induction of the productive cycle and reveals that the BZLF1 protein of Akata virus migrates more slowly on SDS gels than the BZLF1 protein of the prototypic virus strain B95-8. The nucleotide sequence of the BZLF1 gene and the immediate early promoters of Akata EBV have been determined and compared to other EBV strains. RFLP analysis of sequence variation in the BZLF1 gene of EBV strains from many different parts of the world shows a distribution of BZLF1 types which are not simply related to the established A and B EBV types.