In order to enrich the research about type Ⅲ secretion system(T3SS) injectisome of Vibrio alginolyticus,vscX gene was cloned from V.alginolyticus strain HY9901 for bioinformatics analysis and expression analysis.Specific primers were designed according to the full-length genome sequence of V.alginolyticus in GenBank.vscX gene(GenBank accession number:FR780679) contained a 378 bp open reading frame(ORF),encoding a putative protein of 125 amino acids.The theoretical molecular weight was 14.209 2 kD and theoretical pI was 5.75.By using Signal 4.1 Server and TMHMM Server 2.0,it was predicted that VscX protein had no transmembrane domain or signal peptide.The results of prediction using SoftBerry-Psite software showed that VscX protein contained three casein kinase Ⅱ phosphorylation sites,one N-myristoylation site and three C-terminal targeting signal sites.Subcellular localization revealed that VscX might be located in cytoplasm with the possibility of 56.5%.According to SMART prediction,VscX had one Pfam(1-125 aa) domain.Phylogenetic analysis revealed that VscX from V.alginolyticus and VscX from V.parahemolyticus were clustered into the same group.Network interaction analysis showed that vscX was adjacent to vscY,vopB and sycN.By real-time fluorescent quantitative PGR technique and 2~(-△△Ct) method,the differences in expression levels of VscX mRNA in V.alginolyticus strain HY9901,T3 SS deletion strain AvscO and complementary strain C-vscO at different growth stages were analyzed.The results showed that the expression levels of VscX mRNA in V.alginolyticus strain HY9901 and C-vscO were significantly up-regulated at stable growth stage(P<0.01);the expression levels of VscX mRNA in deletion strain AvscO were significantly up-regulated at late growth stage(P <0.01).This study provided the basis for revealing the transport mechanism of T3 SS injectisome of V.alginolyticus. In order to enrich the research about type III secretion system (T3SS) injectisome of Vibrio alginolyticus, vscX gene was cloned from V. alginolyticus strain HY9901 for bioinformatics analysis and expression analysis. Specific primers were designed according to the full-length genome sequence of V .alginolyticus in GenBank. vscX gene (GenBank accession number: FR780679) contained a 378 bp open reading frame (ORF), encoding a putative protein of 125 amino acids. The theoretical molecular weight was 14.209 2 kD and theoretical pI was 5.75.By using Signal 4.1 Server and TMHMM Server 2.0, it was predicted that VscX protein had no transmembrane domain or signal peptide. The results of prediction using SoftBerry-Psite software showed that VscX protein contained three casein kinase Ⅱ phosphorylation sites, one N-myristoylation site and three C-terminal targeting signal sites. Subcellular localization revealed that VscX might be located in cytoplasm with the possibility of 56.5%. Aording to SMART predicti on, VscX had one Pfam (1-125 aa) domain. Phylogenetic analysis revealed that VscX from V. alginolyticus and VscX from V. parahemolyticus were clustered into the same group. Network interaction analysis showed that vscX was adjacent to vscY, vopB and sycN .By real-time fluorescent quantitative PGR technique and 2 ~ (- △△ Ct) method, the differences in expression levels of VscX mRNA in V. alginolyticus strain HY9901, T3 SS deletion strain AvscO and complementary strain C-vscO at different growth stages were analyzed.The results showed that the expression levels of VscX mRNA in V. alginolyticus strain HY9901 and C-vscO were significantly up-regulated at stable growth stage (P <0.01); the expression levels of VscX mRNA in deletion strain AvscO were significantly up-regulated at late growth stage (P <0.01). This study provides the basis for revealing the transport mechanism of T3 SS injecting a V. alginolyticus.