Multilocus variable-number tandem-repeat analysis of Yersinia ruckeri confirms the existence of host specificity, geographic endemism, and anthropogenic dissemination of virulent clones
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Journal articlePeer reviewed
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2018-08Author
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A multilocus variable-number tandem-repeat analysis (MLVA) assay was
developed for epizootiological study of the internationally significant fish pathogen
Yersinia ruckeri, which causes yersiniosis in salmonids. The assay involves amplification of 10 variable-number tandem-repeat (VNTR) loci in two five-plex PCRs, followed by capillary electrophoresis. A collection of 484 Y. ruckeri isolates, originating
from various biological sources and collected from four continents over 7 decades,
was analyzed. Minimum-spanning-tree cluster analysis of MLVA profiles separated
the studied population into nine major clonal complexes and a number of minor
clusters and singletons. The major clonal complexes could be associated with host
species, geographic origin, and serotype. A single large clonal complex of serotype
O1 isolates dominating the yersiniosis situation in international rainbow trout farming suggests anthropogenic spread of this clone, possibly related to transport of fish.
Moreover, subclustering within this clonal complex indicates putative transmission
routes and multiple biotype shift events. In contrast to the situation in rainbow
trout, Y. ruckeri strains associated with disease in Atlantic salmon appear as more or
less geographically isolated clonal complexes. A single complex of serotype O1 exclusive to Norway was found to be responsible for almost all major yersiniosis outbreaks in modern Norwegian salmon farming, and site-specific subclustering further
indicates persistent colonization of freshwater farms in Norway. Identification of genetically diverse Y. ruckeri isolates from clinically healthy fish and environmental
sources also suggests the widespread existence of less-virulent or avirulent strains.
Citation
Gulla S, Barnes AC, Welch, Romalde JL, Ryder, Ormsby, Carson, Lagesen K, Verner-Jeffreys DW, Davies, Colquhoun DJ. Multilocus variable-number tandem-repeat analysis of Yersinia ruckeri confirms the existence of host specificity, geographic endemism, and anthropogenic dissemination of virulent clones. Applied and Environmental Microbiology. 2018;84(16):e00730-18Publisher
American Society for MicrobiologySubject
Atlantic salmonYersinia ruckerifish pathogengeographic endemismhost specificitymolecular typingrainbow troutyersiniosisCollections
Copyright 2018 Gulla et al.