Abstract: Objective To explore the cloning,expression and purification of pemphigus vulgaris (PV)autoantigen desmoglein(Dsg)3,and to utilize the recombinant Dsg 3 to detect pemphigus antibodies in sera of patients with PV.Methods Specific primers were designed aiming the EC1-EC5 fragment of Dsg 3 antigen.The specific gene fragment was amplified with RT-PCR,then inserted into the eukaryotic expression plasmid pcDNA3.1^TM/myc-His(-)B.The recombinant plasmid was then employed to transfect human cervical carcinoma cell line Hela,to express the fusion protein,which was purified with Ni⁺ affinity chromatography.Western blotting method was used to confirm the reactivity of the antigen.ELISA was utilized,with the recombinant protein as antigen,to detect PV antibodies in sera of 40 patients with PV and 40 normal human controls.Results The eukaryotic expression plasmid was successfully established,and the recombinant Dsg3 antigen was successfully expressed.The purified antigen could selectively react with sera from PV patients.ELISA revealed that the positivity rate of PV antibodies was 95% in sera from the PV patients.Conclusion The recombinant autoantigen Dsg3 could specifically react with serum antibodies from PV patients.

Key words: Pemphigus, Recombinant autoantigen, Dsg3 EC1-EC5