Sequence analysis and variation of EBNA-1 in Epstein-Barr virus-related herpesvirus of cynomolgus monkey

The Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA-1) is an important protein for immortalization and tumorigenesis of infected cells. EBNA-1 gene variants may play a role in tumorigenesis. We determined the nucleotide and amino acid (aa) sequences of EBNA-1 in EBV-related herpesviruses from cynomolgus monkeys (cynomolgus-EBV) which induced malignant lymphomas in its natural host and in rabbits, and compared them with sequences of EBV and other lymphocryptoviruses (LCVs).

Polymerase chain reaction and direct sequencing methods were performed using extracted DNA from cynomolgus-EBV-infected cell lines.

The amino acid sequences of cynomolgus-EBV EBNA-1 from two cell lines (Si-IIA: 588 aa; Ts-B6: 619 aa) which are antigenically cross-reactive to human EBV EBNA-1 showed homology with human EBV (Si-IIA: 53%; Ts-B6: 58%) and other LCVs from baboons (54 and 52%) and rhesus monkeys (60 and 58%), especially in the C-terminal unique domain. Homology of the EBNA-1 sequence between Si-IIA and Ts-B6 was 92%. The sequence difference between EBV and the related LCVs was manifested mainly in the length of the internal repeat 3-corresponding region, which contains serine in the glycine/alanine repeat region of nonhuman LCVs.

Sequence variation of cynomolgus-EBV EBNA-1 from different cell lines was observed. However, their sequences show a relatively high homology with human EBV and share the common features of EBNA-1 of EBV and other LCVs.