Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 4648
Title: Microevolution of Renibacterium salmoninarum: evidence for intercontinental dissemination associated with fish movements
Author: Ola Brynildsrud, Edward J. Feil, Jon Bohlin, Santiago Castillo-Ramirez, Duncan Colquhoun, Una McCarthy, Iveta M. Matejusova, Gregory D. Wiens, Linda D. Rhodes, David W. Verner-Jeffreys
Publication Year: 2014
Journal: The International Society for Microbial Ecology Journal
Volume: 8
Issue: 4
Pages: 746-756
DOI: 10.1038/ismej.2013.186
Keywords: pathogen,genotyping,Renibacterium salmoninarum,

 Renibacterium salmoninarum is the causative agent of bacterial kidney disease, a major pathogen of salmonid fish species worldwide. Very low levels of intra-species genetic diversity have hampered efforts to understand the transmission dynamics and recent evolutionary history of this Gram-positive bacterium. We exploited recent advances in the next-generation sequencing technology to generate genome-wide single-nucleotide polymorphism (SNP) data from 68 diverse R. salmoninarumisolates representing broad geographical and temporal ranges and different host species. Phylogenetic analysis robustly delineated two lineages (lineage 1 and lineage 2); futhermore, dating analysis estimated that the time to the most recent ancestor of all the isolates is 1239 years ago (95%credible interval (CI) 444–2720 years ago). Our data reveal the intercontinental spread of lineage 1 over the last century, concurrent with anthropogenic movement of live fish, feed and ova for aquaculture purposes and stocking of recreational fisheries, whilst lineage 2 appears to have been endemic in wild Eastern Atlantic salmonid stocks before commercial activity. The high resolution of the SNP-based analyses allowed us to separate closely related isolates linked to neighboring fish farms, indicating that they formed part of single outbreaks. We were able to demonstrate that the main lineage 1 subgroup of R. salmoninarum isolated from Norway and the UK likely represent an introduction to these areas ~40 years ago. This study demonstrates the promise of this technology for analysis of micro and medium scale evolutionary relationships in veterinary and environmental microorganisms, as well as human pathogens.


 This publication presents phylogenetic & SNP-based analyses of genome sequencing of 68 strains of Renibacterium salmoninarum. 

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Theme: Recovery and rebuilding of marine and coastal species
Foci: Evaluate the effects of artificial propagation on recovery, rebuilding and sustainability of marine and anadromous species.