Characterization of an Epstein-Barr virus nuclear antigen 2 variant (EBNA 2B) by specific sera

The Jijoye Epstein-Barr virus (EBV) strain is characterized by a substitution of 1.8 kb in the C-terminal part of EBNA 2 gene compared to B95-8 or M-ABA virus. Protein immunoblot analysis using human sera against EBNA 2 indicated that an immunological variant to the EBNA 2 of B95-8 (type A) is encoded by the Jijoye virus (type B). In order to generate a specific EBNA 2B antiserum the NaeI/NsiI DNA fragment of the Jijoye virus containing 237 bp of the C-terminus from the EBNA 2B gene was cloned in an E. coli expression vector (pME3). The resulting fusion protein contained 79 C-terminal amino acids of the viral protein and a 37,000 Da part of the bacterial anthranilate synthase. Rabbit antisera generated against this fusion protein reacted specifically with two proteins of 73,000 and 77,000 Da from Jijoye cells and three other cell lines carrying type B virus, while no proteins could be identified in the type B cell line BL 29. In addition, using these sera directed against the pME3 fusion protein, no reaction could be observed with the EBNA 2A protein from the B95-8 and several other cell lines containing type A virus.