The original antibody was generated by immunizing rabbit with a synthetic peptide comprising amino acid sequence SIRLQI(pS)NPDLKDC. The immunogen sequence was phosphorylated at the 7th serine residue which corresponds to serine 446 of human IRF5. A phage display scFv library was generated using the cells from the spleen and the specific antibody was isolated by positive screening against biotinylated SIRLQI(pS)NPDLKDC peptide and negative selection biotinylated non-phosphorylated peptide SIRLQISNPDLKDK.