摘要Objective Hepatitis Delt a Virus (HDV) antigen is widely used as a capture antigen in ELISAs for the identification of HDV infection;large amounts of recombinant HDV antigen with active antigenicity are required for this purpose. <br> Methods Reconstruct the gene of HDV antigen based on the bias code of Escherichia coli, the recombinant protein expresses by high-density fermentation with fed-batch feeding strategy, and purify by immobilized metal chromatography. The sensitivity and specificity of this antigen detect by ELISA method. <br> Results The expression of HDV antigen can reach 20%of the total cell mass in the soluble form. The recombinant HDV antigen can be conveniently purified (98%) by immobilized metal ion affinity chromatography (IMAC) using the interaction between a His-tag and nickel ions. Production of recombinant HDV antigen can reach 0.5 g/L under conditions of high-density cell fermentation. Applied to the diagnostic ELISA method, the recombinant HDV antigen shows excellent sensitivity (97%for IgM and 100%for IgG) and specificity (100%for IgG and IgM) for the detection of anti-HDV antibodies. <br> Conclusion Expression and purification the recombinant HDV antigen as a candidate protein for application in a diagnostic ELISA for HDV infection. Large-scale production of the protein can be achieved using the high-density fermentation strategy.