Sequence analysis on OmpK genes and antigenicity of pathogentic Vibrios isolated from marine fishes

Outer membrane protein OmpK was a kind of receptor for broad-host-range vibriophage.To study whether the OmpK was the common antigen of different Pathogenic Vibrios in marine fish at molecular level,the OmpK genes of V.harveyi,V.alginolyticus and V.parahaemolyticus were cloned and sequenced.19 strains of Pathogenic Vibrios were isolated from different marine fish in Guangdong,Hainan and Fujian province.A pair of degenerate primers were designed and synthesized according to the nucleotide sequence of the OmpK gene of Vibrio reported.Using the total genomes of 19 stains Vibrio as templates,OmpK genes fragments were obtained by PCR amplification and cloned into pMD18-T Vector.Recombinants were confirmed by digesting with restriction enzyme, EcoRⅠand Sal,and then the inserts were sequenced.The result showed that OmpK genes contained an open reading frame of 786?bp-849?bp that coded 261-282 amino acids in 19 strains of Vibrios.The similarities of the nucleotide sequences of OmpK genes were 72%-100% and the deduced amino acid sequences were 71%-100% among 19 strains of Vibrios.As a result,the OmpK genes not only were distributed widely in all tested Vibrios,but also shared quite high similarity in nucleotide sequences and deduced amino acid sequences.So OmpK could be a kind of effective protective common antigen and an effective potential vaccine candidate against different Vibrios.It suggested that the OmpK would be a candidate for subunit vaccine to prevent the disease caused by different Vibrios in marine fish.Among the deduced amino acid sequences of three species of Vibrios,each had a special sequences of 6-9 amino acids which were different from each other.The special sequences would lead to further studies of a rapid and sensitive method to diagnose the pathogenic V.harveyi,V.alginolyticus or V.parahaemolyticus.