This study investigated how Epstein–Barr virus (EBV) nuclear antigen 6 (EBNA6) interacts with RBP-2N, an isoform of the cellular protein RBP-Jκ. Using the yeast two-hybrid system, researchers identified that both EBNA6A (type A virus) and EBNA6B (type B virus) interact with RBP-2N, though EBNA6A binds more efficiently than EBNA6B. Deletion analysis revealed that amino acids 182–440 of EBNA6A are involved in the RBP-2N interaction, while a domain within amino acids 159–331 of RBP-2N mediates binding to EBNA6A. Importantly, the RBP-2N binding region overlaps with where EBNA2, another viral protein, binds—suggesting potential competition between these proteins for RBP-2N. Co-immunoprecipitation experiments confirmed the interaction occurs in infected cells. The weaker binding of EBNA6B to RBP-2N may contribute to reduced transforming activity of type B EBV. These findings provide insights into how different EBV types regulate viral gene expression through interactions with host cell proteins during B lymphocyte transformation.

Key findings

• EBNA6A and EBNA6B both interact with RBP-2N, but EBNA6A binds more strongly than EBNA6B
• Amino acids 182–440 of EBNA6A are required for RBP-2N interaction
• The RBP-2N binding region (amino acids 159–331) overlaps with the EBNA2 binding site, suggesting competition for the same protein
• Differential binding affinities between type A and type B EBV EBNA6 proteins may explain biological differences in viral transformation capacity