title: Pulsed-field gel electrophoresis and multi locus sequence typing for characterizing genotype variability of Yersinia ruckeri isolated from farmed fish in France.
abstract: Yersinia ruckeri is a pathogen that has an impact on aquaculture worldwide. The disease caused by this bacterial species, yersiniosis or redmouth disease, generates substantial economic losses due to the associated mortality and veterinary costs. For predicting outbreaks and improving control strategies, it is important to characterize the population structure of the bacteria. The phenotypic and genetic homogeneities described previously indicate a clonal population structure as observed in other fish bacteria. In this study, the pulsed-field gel electrophoresis (PFGE) and multi locus sequence typing (MLST) methods were used to describe a population of isolates from outbreaks on French fish farms. For the PFGE analysis, two enzymes (NotI and AscI) were used separately and together. Results from combining the enzymes showed the great homogeneity of the outbreak population with a similarity > 80.0% but a high variability within the cluster (cut-off value = 80.0%) with a total of 43 pulsotypes described and an index of diversity = 0.93. The dominant pulsotypes described with NotI (PtN4 and PtN7) have already been described in other European countries (Finland, Germany, Denmark, Spain and Italy). The MLST approach showed two dominant sequence types (ST31 and ST36), an epidemic structure of the French Y. ruckeri population and a preferentially clonal evolution for rainbow trout isolates. Our results point to multiple types of selection pressure on the Y. ruckeri population attributable to geographical origin, ecological niche specialization and movements of farmed fish.
authors.affiliation: LUNAM Université, Oniris, École nationale vétérinaire, agroalimentaire et de l'alimentation Nantes-Atlantique, UMR1300 Biologie, Épidémiologie et Analyse de Risque en santé animale, F-44307, Nantes, France. segolene.calvez@oniris-nantes.fr.|INRA, UMR1300 BioEpAR, F-44307, Nantes, France. segolene.calvez@oniris-nantes.fr.
authors.forename: Ségolène
authors.initials: S
authors.lastname: Calvez
authors.affiliation: LUNAM Université, Oniris, École nationale vétérinaire, agroalimentaire et de l'alimentation Nantes-Atlantique, UMR1300 Biologie, Épidémiologie et Analyse de Risque en santé animale, F-44307, Nantes, France. catherine.fournel@oniris-nantes.fr.|INRA, UMR1300 BioEpAR, F-44307, Nantes, France. catherine.fournel@oniris-nantes.fr.
authors.forename: Catherine
authors.initials: C
authors.lastname: Fournel
authors.affiliation: GDSAA, Groupe de Défense Sanitaire Aquacole Aquitain, F-40000, Mont de Marsan, France. dgdouet@yahoo.fr.
authors.forename: Diane-Gaëlle
authors.initials: DG
authors.lastname: Douet
authors.affiliation: Laboratoire des Pyrénées et des Landes, F-40000, Mont de Marsan, France. p.daniel@labopl.com.
authors.forename: Patrick
authors.initials: P
authors.lastname: Daniel
mesh_terms: D000818:Animals; D017756:Aquaculture; D016521:Electrophoresis, Gel, Pulsed-Field / Q000662:veterinary; D005393:Fish Diseases / Q000235:genetics* / Q000382:microbiology; D005602:France; D014644:Genetic Variation; D058885:Multilocus Sequence Typing / Q000662:veterinary; D017686:Oncorhynchus mykiss; D015009:Yersinia Infections / Q000235:genetics / Q000382:microbiology / Q000662:veterinary*; D044124:Yersinia ruckeri / Q000235:genetics*