A conserved outer membrane protein as an effective vaccine candidate from Vibrio alginolyticus

Vibrio alginolyticus, a Gram-negative bacterium, is one of the Vibrio pathogens common to human and marine animals. Outer membrane proteins of bacteria play an important role during infection and induction of host immune response. In present research, the OmpK gene of V. alginolyticus was cloned and expressed. The open reading frame contains 846 bp, and the mature protein consists of 261 amino acid residues. The alignment analysis indicated that OmpK was highly conserved, which could serve as a surface antigen for good vaccine candidate. SDS-PAGE indicated the OmpK could over-express in E. coli BL21 (DE3). The recombinant protein was purified by affinity chromatography on Ni-NTA Superflow resin. Western blot analysis revealed that the OmpK protein had immunoreactivity. The large yellow croakers vaccinated with the OmpK were significantly protected against the infection by V. alginolyticus. This study showed that the conserved OmpK was an effective vaccine candidate against infection by V. alginolyticus.