title: Monomorphic genotypes within a generalist lineage ofCampylobacter jejunishow signs of global dispersion.
abstract: The decreased costs of genome sequencing have increased the capability to apply whole-genome sequencing to epidemiological surveillance of zoonoticCampylobacter jejuni.However, knowledge of the genetic diversity of this bacteria is vital for inferring relatedness between epidemiologically linked isolates and a necessary prerequisite for correct application of this methodology. To address this issue inC. jejuniwe investigated the spatial and temporal signals in the genomes of a major clonal complex and generalist lineage, ST-45 CC, by analysing the population structure and genealogy as well as applying genome-wide association analysis of 340 isolates from across Europe collected over a wide time range. The occurrence and strength of the geographical signal varied between sublineages and followed the clonal frame when present, while no evidence of a temporal signal was found. Certain sublineages of ST-45 formed discrete and genetically isolated clades containing isolates with extremely similar genomes regardless of time and location of sampling. Based on a separate data set, these monomorphic genotypes represent successfulC. jejuniclones, possibly spread around the globe by rapid animal (migrating birds), food or human movement. In addition, we observed an incongruence between the genealogy of the strains and multilocus sequence typing (MLST), challenging the existing clonal complex definition and the use of whole-genome gene-by-gene hierarchical nomenclature schemes forC. jejuni.
authors.affiliation: 1​Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland.
authors.forename: Ann-Katrin
authors.initials: AK
authors.lastname: Llarena
authors.affiliation: 2​Institute of Veterinary, Animal & Biomedical Sciences, College of Sciences, Massey University, Palmerstone North, New Zealand.
authors.forename: Ji
authors.initials: J
authors.lastname: Zhang
authors.affiliation: 3​Department of Mathematics and Statistics, Faculty of Science, University of Helsinki, Helsinki, Finland.
authors.forename: Minna
authors.initials: M
authors.lastname: Vehkala
authors.affiliation: 4​Department of Medical and Clinical Genetics, Genome-Scale Biology Research Program, University of Helsinki, Helsinki, Finland.
authors.forename: Niko
authors.initials: N
authors.lastname: Välimäki
authors.affiliation: 5​Food and Feed Microbiology Research Unit, Research and Laboratory Department, Finnish Food Safety Authority Evira, Helsinki, Finland.
authors.forename: Marjaana
authors.initials: M
authors.lastname: Hakkinen
authors.affiliation: 1​Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland.
authors.forename: Marja-Liisa
authors.initials: ML
authors.lastname: Hänninen
authors.affiliation: 6​Department of Food Hygiene, Institute of Veterinary Medicine and Animal Sciences, Estonian University of Life Sciences, Tartu, Estonia.
authors.forename: Mati
authors.initials: M
authors.lastname: Roasto
authors.affiliation: 6​Department of Food Hygiene, Institute of Veterinary Medicine and Animal Sciences, Estonian University of Life Sciences, Tartu, Estonia.|7​Veterinary and Food Laboratory, VFL, Tartu, Estonia.
authors.forename: Mihkel
authors.initials: M
authors.lastname: Mäesaar
authors.affiliation: 8​National Microbiology Laboratory, Public Health Agency of Canada, c/o Animal Diseases Research Institute, Lethbridge, Canada.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Taboada
authors.affiliation: 8​National Microbiology Laboratory, Public Health Agency of Canada, c/o Animal Diseases Research Institute, Lethbridge, Canada.
authors.forename: Dillon
authors.initials: D
authors.lastname: Barker
authors.affiliation: 9​National Reference Laboratory for Campylobacter, Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise 'G. Caporale', Teramo, Italy.
authors.forename: Giuliano
authors.initials: G
authors.lastname: Garofolo
authors.affiliation: 9​National Reference Laboratory for Campylobacter, Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise 'G. Caporale', Teramo, Italy.
authors.forename: Cesare
authors.initials: C
authors.lastname: Cammà
authors.affiliation: 9​National Reference Laboratory for Campylobacter, Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise 'G. Caporale', Teramo, Italy.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Di Giannatale
authors.affiliation: 10​Institute of Basic Medical Sciences, Department of Biostatistics, Faculty of Medicine, University of Oslo, Oslo, Norway.
authors.forename: Jukka
authors.initials: J
authors.lastname: Corander
authors.affiliation: 1​Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland.
authors.forename: Mirko
authors.initials: M
authors.lastname: Rossi
mesh_terms: D000818:Animals; D002169:Campylobacter Infections / Q000382:microbiology; D016123:Campylobacter jejuni / Q000235:genetics*; D003710:Demography; D005060:Europe; D016680:Genome, Bacterial / Q000235:genetics; D055106:Genome-Wide Association Study; D005838:Genotype; D006801:Humans; D058885:Multilocus Sequence Typing
keywords: Campylobacter jejuni; genomic epidemiology; monomorphic clones; whole-genome sequencing