There were eight T3SS2α-positive and one T3SS2β-positive strain among the T3SS2-positive V. mimicus strains. The gene organization of the T3SS2 gene cluster in the V. mimicus strains containing

T3SS2α or T3SS2β, was basically similar to that of the VRT752271 price V. parahaemolyticus and V. cholerae strains. Ours is thus the first study to demonstrate that the two distinct types of T3SS2 gene clusters, T3SS2α and T3SS2β, are present not only in V. parahaemolyticus and V. cholerae but also in V. mimicus strains. Furthermore, we could show that the structures of the V. mimicus PAIs containing the T3SS genes may be more closely related to those of V. cholerae VPI-2 than of V. parahaemolyticus Vp-PAI (Figure 2). In contrast, the ORFs in VPI-2 were not detected in any of the T3SS-negative V. mimicus strains. This implies, therefore, that the similar PAI cassettes containing the T3SS2 gene cluster were acquired through horizontal gene transfer

in V. cholerae and V. mimicus (Figure 3). Figure 3 Schematic representation of the MK5108 cost hypothetical evolutionary acquisition of the T3SS-related gene cluster in V. parahaemolyticus , V. cholerae and V. mimicus. Lineage is based on the presence of each of the determinants, for example, tdh, trh, CTX and T3SS2. Sotrastaurin mouse The shaded ellipses show the T3SS-related gene clusters, bold lines represent the evolutionary process, and circles represent the strains of V. parahaemolyticus, V. cholerae and V. mimicus, while shaded circles

indicate that the strains possess T3SSα or T3SSβ. Broken lines indicate that the T3SS gene clusters or CTX have been acquired by horizontal gene transfer while the organisms were evolving. The PCR primer pairs used in this study were found to be useful for detecting as well as distinguishing the genes for T3SS2α and T3SS2β in Vibrio species. In particular, the PCR assays targeting the three genes, vscN2, vscR2 and vscT2, (-)-p-Bromotetramisole Oxalate produced stable and reliable results for detection of T3SS2-related genes. We therefore consider that, for determining the presence or absence of these genes, PCR amplification using the primer pairs for the vscN2R2T2 genes of T3SS2α or T3SS2β is effective and rapid. Although only a limited number of strains of the non-human pathogenic Vibrio species was examined in this study, more extensive studies of those species using more strains may well reveal the presence of the T3SS2 genes in vibrios other than the ones reported here. Previous studies showed that the T3SSs of V. parahaemolyticus and V. cholerae contribute to their pathogenicity for humans [14, 17, 20, 22–24]. In V. mimicus, a bacterium which is known to be a causative agent of gastroenteritis in humans, the hemolysin was previously reported as a major virulence factor [26]. To assess the function of T3SS of V. mimicus in pathogenicity in our study, we evaluated the cytotoxicity of V. mimicus for Caco-2 cells because V.