Native early antigen of Epstein-Barr virus, a promising antigen for diagnosis of nasopharyngeal carcinoma.
The Epstein-Barr virus (EBV) early antigen (EA) complex consists of multiple proteins with relevance for diagnosis of acute, chronic and malignant EBV related diseases, including nasopharyngeal carcinoma (NPC). In a recent study, it was found that the molecular diversity of EBV-specific IgG and IgA antibody responses in NPC patients and demonstrated that these reflect independent B-cell triggering leading to distinct EBV antigen-recognition profiles. The fine-specificity of NPC-related IgG and IgA responses was explored further against defined recombinant and synthetic EBV-EA antigens using immunofluorescence, immunoblot and ELISA techniques and determined their diagnostic value in a large panel of sera from NPC (n = 154), non-NPC tumor patients (n = 133), acute mononucleosis patients (n = 70) and healthy EBV carriers (n = 259). Individual recombinant EBV-EA markers yielded sensitivity/specificity values not exceeding 86%, whereas selected EA-specific peptide epitopes were rather poorly recognized by IgG and IgA antibodies in NPC sera. Surprisingly, we found that a "low salt" native EA-protein extract reproducibly prepared from purified nuclei of EA-induced HH514 cells, and containing characteristic EA(D)-polypeptides, such as p47-54 (BMRF1), p138 (BALF2), p55-DNAse (BGLF5), and p65-TK (BXLF1), but without viral capsid (VCA) or nuclear antigen (EBNA) reactivity, gave highest sensitivity (90.4%) and specificity (95.5%) values for NPC diagnosis in both IgG and IgA ELISA. The data support further the notion that EBV-EA reactive IgG and IgA antibodies in NPC patients are directed against distinct conformational and-in part-linear epitopes on EBV-specific proteins, barely recognized in other EBV-related syndromes. The use of a defined native EBV EA-specific antigen opens the way to further improve serological diagnosis of NPC.
Paramita
Dewi K
DK
Department of Histology and Cell Biology, Faculty of Medicine Gadjah Mada University, Yogyakarta, Indonesia.
Fachiroh
Jajah
J
Artama
Wayan T
WT
van Benthem
Eric
E
Haryana
Sofia M
SM
Middeldorp
Jaap M
JM
D000818:Animals; D000956:Antigens, Viral / Q000235:genetics / Q000276:immunology; D016367:Baculoviridae / Q000235:genetics; D002460:Cell Line; D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay; D004854:Herpesvirus 4, Human / Q000276:immunology*; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D009303:Nasopharyngeal Neoplasms / Q000175:diagnosis* / Q000821:virology; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology; D018411:Spodoptera
D000956:Antigens, Viral; C033305:Epstein-Barr virus early antigen; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D011994:Recombinant Proteins