title: Genetic characterization of trh positive Vibrio spp. isolated from Norway.
abstract: The thermostable direct hemolysin (TDH) and/or TDH-related hemolysin (TRH) genes are carried by most virulent Vibrio parahaemolyticus serovars. In Norway, trh+ V. parahaemolyticus constitute 4.4 and 4.5% of the total number of V. parahaemolyticus isolated from blue mussel (Mytilus edulis) and water, respectively. The trh gene is located in a region close to the gene cluster for urease production (ure). This region was characterized in V. parahaemolyticus strain TH3996 and it was found that a nickel transport operon (nik) was located between the first gene (ureR) and the rest of the ure cluster genes. The organization of the trh-ureR-nik-ure gene cluster in the Norwegian trh+ isolates was unknown. In this study, we explore the gene organization within the trh-ureR-nik-ure cluster for these isolates. PCR analyses revealed that the genes within the trh-ureR-nik-ure gene cluster of Norwegian trh+ isolates were organized in a similar fashion as reported previously for TH33996. Additionally, the phylogenetic relationship among these trh+ isolates was investigated using Multilocus Sequence Typing (MLST). Analysis by MLST or ureR-trh sequences generated two different phylogenetic trees for the same strains analyzed, suggesting that ureR-trh genes have been acquired at different times in Norwegian V. parahaemolyticus isolates. MLST results revealed that some pathogenic and non-pathogenic V. parahaemolyticus isolates in Norway appear to be highly genetically related.
authors.affiliation: Department of Food Safety and Infection Biology, Norwegian School of Veterinary Science Oslo, Norway.
authors.forename: Anette B
authors.initials: AB
authors.lastname: Ellingsen
authors.affiliation: Norwegian Defence Research Establishment Kjeller, Norway.
authors.forename: Jaran S
authors.initials: JS
authors.lastname: Olsen
authors.affiliation: Department of Food Safety and Infection Biology, Norwegian School of Veterinary Science Oslo, Norway.
authors.forename: Per E
authors.initials: PE
authors.lastname: Granum
authors.affiliation: Department of Food Safety and Infection Biology, Norwegian School of Veterinary Science Oslo, Norway.
authors.forename: Liv M
authors.initials: LM
authors.lastname: Rørvik
authors.affiliation: Food and Drug Administration, Center for Food Safety and Applied Nutrition College Park, MD, USA.
authors.forename: Narjol
authors.initials: N
authors.lastname: González-Escalona
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics*; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D023061:Gene Order; D006460:Hemolysin Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D005810:Multigene Family; D058885:Multilocus Sequence Typing; D049880:Mytilus edulis / Q000382:microbiology; D009664:Norway; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D017385:Sequence Homology; D014736:Vibrio parahaemolyticus / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D006460:Hemolysin Proteins; C088609:thermostable direct hemolysin-related hemolysin protein, Vibrio parahaemolyticus
keywords: MLST; PCR; V. alginolyticus; V. parahaemolyticus; Vibrio; tdh; trh; urease