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Diseases of Aquatic Organisms

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DAO 84:25-33 (2009)  -  DOI:

Yersinia ruckeri biotype 2 isolates from mainland Europe and the UK likely represent different clonal groups

Richard W. Wheeler1,2,6, Robert L. Davies2, Inger Dalsgaard3, Jose Garcia4,7, Timothy J. Welch5, Sariqa Wagley1, Kelly S. Bateman1, David W. Verner-Jeffreys1,*

1Cefas Weymouth Laboratory, The Nothe, Barrack Road, Weymouth, Dorset DT4 8UB, UK
2Division of Infection and Immunity, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow G12 8TA, UK
3Fish Disease Laboratory, National Institute of Aquatic Resources, Technical University of Denmark, Stigbøjlen 4,
1870 Frederiksberg C, Denmark
4Universidad Complutense de Madrid, Madrid, Spain
5USDA/ARS National Center for Cool and Cold Water Aquaculture, 11861 Leetown Rd., Kearneysville, West Virginia 25430, USA
6Present address: F 18 Foster Lab, Firth Court, Western Bank, University of Sheffield, Sheffield S10 2TN, UK
7Present address: Dpto. Sanidad Animal, Fac. Veterinaria-UCM Avda, Puerta de Hierro s/n, 28040 Madrid, Spain
*Corresponding author. Email:

ABSTRACT: There have been increased reports of outbreaks of enteric redmouth disease (ERM) caused by Yersinia ruckeri in previously vaccinated salmonids in Europe, with some of these outbreaks being attributed to emergent non-motile, Tween 80-negative, biotype 2 isolates. To gain information about their likely origins and relationships, a geographically and temporally diverse collection of isolates were characterised by serotyping, biotyping, pulsed-field gel electrophoresis (PFGE) and outer membrane protein (OMP) profiling. A total of 44 pulsotypes were identified from 160 isolates by PFGE, using the restriction enzyme NotI. Serotype O1 isolates responsible for ERM in rainbow trout in both the US and Europe, and including biotype 2 isolates, represented a distinct subgroup of similar pulsotypes. Biotype 2 isolates, responsible for outbreaks of the disease in rainbow trout in the UK, Denmark and Spain, had different pulsotypes, suggesting that they represented different clones that may have emerged separately. Danish biotype 2 isolates recovered since 1995 were indistinguishable by PFGE from the dominant biotype 1 clone responsible for the majority of outbreaks in Denmark and the rest of mainland Europe. In contrast, US biotype 2 isolate YRNC10 had an identical pulsotype and OMP profile to UK biotype 2 isolates, suggesting that there had been exchange of these isolates between the UK and the US in the past. UK Atlantic salmon isolates were genetically and serologically diverse, with 12 distinct pulsotypes identified among 32 isolates.

KEY WORDS: Yersinia ruckeri · Pulsed-field gel electrophoresis · PFGE · Enteric redmouth disease · ERM · Biotype · Emerging strain

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Cite this article as: Wheeler RW, Davies RL, Dalsgaard I, Garcia J and others (2009) Yersinia ruckeri biotype 2 isolates from mainland Europe and the UK likely represent different clonal groups. Dis Aquat Org 84:25-33.

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