The presence of autoantibodies against citrullinated proteins in rheumatoid arthritis patients was first described in the mid-seventies when the biochemical basis of antibody reactivity against keratin and filaggrin was investigated. Subsequent studies demonstrated that autoantibodies from RA patients react with a series of different citrullinated antigens, including fibrinogen, deiminated Epstein-Barr Virus Nuclear Antigen 1 and vimentin, which is a member of the intermediate filament family of proteins. Several assays for detecting ACPAs were developed in the following years, employing mutated citrullinated Vimentin (MCV-assay), filaggrin derived peptides (CCP-assay), viral citrullinated peptides (VCP-assay).Viral Citrullinated Peptides, one of the antigen target of Anti-citrullinated protein antibody in rheumatoid arthritis .