Multilocus variable-number tandem-repeat analysis of Yersinia ruckeri confirms the existence of host specificity, geographic endemism, and anthropogenic dissemination of virulent clones

Gulla, S. et al. (2018) 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, 84(16), e00730-18. (doi: 10.1128/AEM.00730-18) (PMID:29884756) (PMCID:PMC6070765)

Abstract

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.

• Item Type: Articles
• Additional Information: This study was financed by the Norwegian Seafood Research Fund - FHF (project no. 901119).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Ormsby, Dr Michael and Davies, Dr Robert
• Authors: Gulla, S., Barnes, A. C., Welch, T. J., Romalde, J. L., Ryder, D., Ormsby, M. J., Carson, J., Lagesen, K., Verner-Jeffreys, D. W., Davies, R. L., Colquhoun, D. J., and Cann, I.
• College/School: College of Medical Veterinary and Life Sciences > School of Infection & Immunity
• Journal Name: Applied and Environmental Microbiology
• Publisher: American Society for Microbiology
• ISSN: 0099-2240
• ISSN (Online): 1098-5336
• Published Online: 08 June 2018
• Copyright Holders: Copyright © 2018 Gulla et al.
• First Published: First published in Applied and Environmental Microbiology 84(16): e00730-18
• Publisher Policy: Reproduced under a Creative Commons License