Distinction between Epstein-Barr virus type A (EBNA 2A) and type B (EBNA 2B) isolates extends to the EBNA 3 family of nuclear proteins.
The Epstein-Barr virus (EBV) nuclear antigens EBNA 3a, 3b, and 3c have recently been mapped to adjacent reading frames in the BamHI L and E fragments of the B95.8 EBV genome. We studied by immunoblotting the expression of the family of EBNA 3 proteins in a panel of 20 EBV-transformed lymphoblastoid cell lines (LCLs) carrying either type A (EBNA 2A-encoding) or type B (EBNA 2B-encoding) virus isolates. Certain human sera from donors naturally infected with type A isolates detected the EBNA 3a, 3b, and 3c proteins in all type A virus-transformed LCLs (with a single exception in which EBNA 3b was not detected) but detected only EBNA 3a in LCLs carrying type B isolates. These results were confirmed with human and murine antibodies with specific reactivity against sequences of the type A EBNA 3a, 3b, or 3c expressed in bacterial fusion proteins. Conversely, selected human sera from donors naturally infected with type B strains of EBV identified the EBNA 3a encoded by both types of isolates plus two novel EBNAs present only in type B, and not in type A, virus-transformed LCLs; these novel proteins appear to be the type B homologs of EBNA 3b and 3c. The distinction between type A and type B EBV isolates therefore extends beyond the EBNA 2 gene to the EBNA 3 family of proteins. This has important implications with respect to the evolutionary origin of these two EBV types and also places in a new light recent studies which identified differences between type A and type B transformants in terms of growth phenotype (A. B. Rickinson, L. S. Young, and M. Rowe, J. Virol. 61:1310-1317, 1987) and of detection by EBV-specific cytotoxic T cells (D. J. Moss, I. S. Misko, S. R. Burrows, K. Burman, R. McCarthy, and T. B. Sculley, Nature [London] 331:719-721, 1988).
Rowe
M
M
Department of Cancer Studies, University of Birmingham, England.
Young
L S
LS
Cadwallader
K
K
Petti
L
L
Kieff
E
E
Rickinson
A B
AB
D000911:Antibodies, Monoclonal / Q000276:immunology; D000956:Antigens, Viral / Q000145:classification / Q000276:immunology*; D015153:Blotting, Western; D019309:Epstein-Barr Virus Nuclear Antigens; D004854:Herpesvirus 4, Human / Q000145:classification / Q000276:immunology*; D008214:Lymphocytes / Q000382:microbiology; D008970:Molecular Weight; D009687:Nuclear Proteins / Q000145:classification / Q000276:immunology*; D011233:Precipitin Tests
D000911:Antibodies, Monoclonal; D000956:Antigens, Viral; D019309:Epstein-Barr Virus Nuclear Antigens; D009687:Nuclear Proteins