Presence of genes for type III secretion system 2 in Vibrio mimicus strains.
BACKGROUND
Vibrios, which include more than 100 species, are ubiquitous in marine and estuarine environments, and several of them e.g. Vibrio cholerae, V. parahaemolyticus, V. vulnificus and V. mimicus, are pathogens for humans. Pathogenic V. parahaemolyticus strains possess two sets of genes for type III secretion system (T3SS), T3SS1 and T3SS2. The latter are critical for virulence of the organism and be classified into two distinct phylogroups, T3SS2α and T3SS2β, which are reportedly also found in pathogenic V. cholerae non-O1/non-O139 serogroup strains. However, whether T3SS2-related genes are present in other Vibrio species remains unclear.


RESULTS
We therefore examined the distribution of the genes for T3SS2 in vibrios other than V. parahaemolyticus by using a PCR assay targeting both T3SS2α and T3SS2β genes. Among the 32 Vibrio species tested in our study, several T3SS2-related genes were detected in three species, V. cholerae, V. mimicus and V. hollisae, and most of the essential genes for type III secretion were present in T3SS2-positive V. cholerae and V. mimicus strains. Moreover, both V. mimicus strains possessing T3SS2α and T3SS2β were identified. The gene organization of the T3SS2 gene clusters in V. mimicus strains was fundamentally similar to that of V. parahaemolyticus and V. cholerae in both T3SS2α- and T3SS2β-possessing strains.


CONCLUSIONS
This study is the first reported evidence of the presence of T3SS2 gene clusters in V. mimicus strains. This finding thus provides a new insight into the pathogenicity of the V. mimicus species.
Laboratory of Genomic Research on Pathogenic Bacteria, International Research Center for Infectious Diseases, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan.
Natsumi
N
Okada
Shigeaki
S
Matsuda
Junko
J
Matsuyama
Kwon-Sam
KS
Park
Calvin
C
de los Reyes
Kazuhiro
K
Kogure
Takeshi
T
Honda
Tetsuya
T
Iida
D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D018938:Caco-2 Cells; D002460:Cell Line; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D014733:Vibrio / Q000145:classification / Q000235:genetics / Q000378:metabolism; D014735:Vibrio Infections / Q000382:microbiology*; D044164:Vibrio mimicus / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; D037521:Virulence Factors