Purity > 85% as determined by SDS-PAGE. MW: 22.2kDa. Partial: 1-138aa. N-terminal 10xHis-tagged and C-terminal Myc-tagged. Epstein-Barr virus (strain B95-8) (HHV-4) (Human herpesvirus 4). Plays an essential role for activation and immortalization of human B-cells. Represses transcription of viral promoters TP1 and Cp through interaction with host RBPJ, and inhibits EBNA2-mediated activation of these promoters. Since Cp is the promoter for all EBNA mRNAs, EBNA3A probably contributes to a negative autoregulatory control loop.