[Objective] This study aimed to clone the E. coil NrfA gene and construct the pET-28a （＋）-NrfA prokaryotic expression vector for preparation of polyclonal anti- body against E. coil NrfA. [Method] E. coil NrfA gene was cloned from the E. coli genome DNA by PCR and inserted into the vector pET-28a（＋） to construct prokary- otic expression vector pET-28a （＋）-NrfA. E. coil NrfA protein was expressed by IPTG induction and purified. Polyclonal antibody against NrfA protein was prepared by im- munizing rabbit with routine method. The specificity and titer of polyclonal antibody was confirmed by ELISA and Western Blotting. [Result] The constructed prokaryotic expression vector pET-28a（＋）-NrfA was induced by IPTG, the recombinant NrfA pro- tein could be expressed effectively. The titer of rabbit anti-NrfA polyclonal antibody obtained by immunization and purification was about 1：204 900. Western Blotting anal- ysis indicated that the obtained polyclonal antibody against E. coil NrfA protein had high titer and high specificity. [Conclusion] E. coil NrfA gene was cloned and the prokaryotic expression vector pET-28a （＋）-NrfA was constructed successfully, poly- clonal antibody with high titer and high specificity was prepared, which laid the foun- dation for the study of NrfA in different strains of bacteria.
