title: Genomic Features of Environmental and Clinical Vibrio parahaemolyticus Isolates Lacking Recognized Virulence Factors Are Dissimilar.
abstract: Vibrio parahaemolyticus is a bacterial pathogen that can cause illness after the consumption or handling of contaminated seafood. The primary virulence factors associated with V. parahaemolyticus illness are thermostable direct hemolysin (TDH) and Tdh-related hemolysin (TRH). However, clinical strains lacking tdh and trh have recently been isolated, and these clinical isolates are poorly understood. To help understand the emergence of clinical tdh- and trh-negative isolates, a genomic approach was used to comprehensively compare 4 clinical tdh- and trh-negative isolates with 16 environmental tdh- and trh-negative isolates and 34 clinical isolates positive for tdh or trh, or both, with the objective of identifying genomic features that are unique to clinical tdh- and trh-negative isolates. The prevalence of pathogenicity islands (PAIs) common to clinical isolates was thoroughly examined in each of the clinical tdh- and trh-negative isolates. The tdh PAI was not present in any clinical or environmental tdh- and trh-negative isolates. The trh PAI was not present in any environmental isolates; however, in clinical tdh- and trh-negative isolate 10-4238, the majority of the trh PAI including a partial trh1 gene was present, which resulted in reclassification of this isolate as a tdh-negative and trh-positive isolate. In the other clinical tdh- and trh-negative isolates, neither the trh gene nor the trh PAI was present. We identified 862 genes in clinical tdh- and trh-negative isolates but not in environmental tdh- and trh-negative isolates. Many of these genes are highly homologous to genes found in common enteric bacteria and included genes encoding a number of chemotaxis proteins and a novel putative type VI secretion system (T6SS) effector and immunity protein (T6SS1). The availability of genome sequences from clinical V. parahaemolyticus tdh- and trh-negative isolates and the comparative analysis may help provide an understanding of how this pathotype is able to survive in vivo during clinical illness.
authors.affiliation: Microbiology Research Division, Bureau of Microbial Hazards, Food Directorate, Health Products and Food Branch, Health Canada, Ottawa, Ontario, Canada Jennifer.Ronholm@hc-sc.gc.ca.
authors.forename: J
authors.initials: J
authors.lastname: Ronholm
authors.affiliation: Biostatistics and Modelling Division, Bureau of Food Surveillance and Science Integration, Food Directorate, Health Products and Food Branch, Health Canada, Ottawa, Ontario, Canada.
authors.forename: N
authors.initials: N
authors.lastname: Petronella
authors.affiliation: Microbiology Research Division, Bureau of Microbial Hazards, Food Directorate, Health Products and Food Branch, Health Canada, Ottawa, Ontario, Canada.
authors.forename: C
authors.initials: C
authors.lastname: Chew Leung
authors.affiliation: Microbiology Research Division, Bureau of Microbial Hazards, Food Directorate, Health Products and Food Branch, Health Canada, Ottawa, Ontario, Canada.
authors.forename: A W
authors.initials: AW
authors.lastname: Pightling
authors.affiliation: Microbiology Research Division, Bureau of Microbial Hazards, Food Directorate, Health Products and Food Branch, Health Canada, Ottawa, Ontario, Canada.
authors.forename: S K
authors.initials: SK
authors.lastname: Banerjee
mesh_terms: D004783:Environmental Microbiology; D014644:Genetic Variation; D016680:Genome, Bacterial; D044404:Genomic Islands; D023281:Genomics; D006460:Hemolysin Proteins / Q000235:genetics; D014735:Vibrio Infections / Q000382:microbiology*; D014736:Vibrio parahaemolyticus / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D037521:Virulence Factors / Q000235:genetics
chemical_list: D006460:Hemolysin Proteins; D037521:Virulence Factors