Deiminated Epstein-Barr virus nuclear antigen 1 is a target of anti-citrullinated protein antibodies in rheumatoid arthritis.
OBJECTIVE
To test the hypothesis that deimination of viral sequences containing Arg-Gly repeats could generate epitopes recognized by anti-citrullinated protein antibodies (ACPAs) that are present in rheumatoid arthritis (RA) sera.


METHODS
Multiple antigen peptides derived from Epstein-Barr virus (EBV)-encoded Epstein-Barr nuclear antigen 1 (EBNA-1) were synthesized, substituting the arginines with citrulline, and were used to screen RA sera. Anti-cyclic citrullinated peptide antibodies were purified by affinity chromatography and tested on a panel of in vitro deiminated proteins. Their ability to bind in vivo deiminated proteins was evaluated by immunoprecipitation, using EBV-infected cell lines.


RESULTS
Antibodies specific for a peptide corresponding to the EBNA-1(35-58) sequence containing citrulline in place of arginine (viral citrullinated peptide [VCP]) were detected in 50% of RA sera and in <5% of normal and disease control sera. In addition, affinity-purified anti-VCP antibodies from RA sera reacted with filaggrin-derived citrullinated peptides, with deiminated fibrinogen, and with deiminated recombinant EBNA-1. Moreover, anti-VCP antibodies immunoprecipitated, from the lysate of calcium ionophore-stimulated lymphoblastoid cell lines, an 80-kd band that was reactive with a monoclonal anti-EBNA-1 antibody and with anti-modified citrulline antibodies.


CONCLUSIONS
These data indicate that ACPAs react with a viral deiminated protein and suggest that EBV infection may play a role in the induction of these RA-specific antibodies.
Pratesi
Federico
F
University of Pisa, Pisa, Italy.
Tommasi
Cristina
C
Anzilotti
Consuelo
C
Chimenti
Daniele
D
Migliorini
Paola
P
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000595:Amino Acid Sequence; D000914:Antibodies, Viral / Q000276:immunology*; D001172:Arthritis, Rheumatoid / Q000276:immunology*; D002846:Chromatography, Affinity; D002956:Citrulline / Q000032:analysis; D020031:Epstein-Barr Virus Infections / Q000276:immunology; D019309:Epstein-Barr Virus Nuclear Antigens / Q000737:chemistry* / Q000276:immunology*; D005260:Female; D000091344:Filaggrin Proteins; D006801:Humans; D008297:Male; D008875:Middle Aged; D009698:Nucleoproteins / Q000276:immunology
D000914:Antibodies, Viral; D019309:Epstein-Barr Virus Nuclear Antigens; C000717249:FLG protein, human; D000091344:Filaggrin Proteins; D009698:Nucleoproteins; C090319:peptide 31D; D002956:Citrulline