Abstract: Vibrio vulnificus is an important pathogen that causes the eel sepsis.In this study,the outer membrane protein U(ompU)gene of Vibrio vulnificus strain FJ03-X2is cloned,and then inserted into the prokaryotic expression vector,named pET32a-ompU.The plasmid was then transformed into E.coli strain to induce the expression of rompU protein.The soluble rompU protein can be expressed under the induction of IPTG(0.5mmol/ L)at 37℃for 4h.Then purified it by Ni-NTA His Binding affinity purification.SDS-PAGE displayed the purified rompU as a single band of the expected size.The purified rompU protein was then injected into SD level rats to produce polyclonal antibody.High specificity antiserum of FJ03-X2rompU is confirmed by ELISA detection.Western-blot confirmed that OmpU polyclonal antibodies can recognize the natural outer membrane protein OmpU in Vibrio vulnificus FJ03-X2.