Objective    To express interferon regulatory factor 4 binding protein (IBP)

a novel conserved molecule engaging in autoimmune response

and prepare its polyclonal antibodies.     Methods    IBP specific fragment (1 228-1 893 bp) selected by means of bioinformatic methods

was subcloned into prokaryotic expression vectors pET32a and pGEX-KG

and then the recombinant plasmids were transformed into BL21 respectively and induced by IPTG. The objective fusion proteins were purified by affinity chromatogram with His or GST and negion exchange columns. Rabbit polyclonal antibody serum was prepared by a modified rapid immune procedure followed by purification of protein A column. The titer and specificity of the antibody were determined by ELISA

Western blotting and immunohistochemistry.     Results    HPLC indicated that the purity of pET32a/IBP and pGEX-KG/IBP fusion protein was 92% and 87%

respectively. The titer of the final purified antibodies was up to 1∶51 200. Western blotting and immunohistochemistry revealed that the final purified antibodies were highly specific to native IBP both in human and murine cells.     Conclusion    The specific IBP fusion protein is obtained. The final purified polyclonal antibodies against IBP have specificity to native IBP.