DAO 117:121-131 (2015)  -  DOI: https://doi.org/10.3354/dao02938

Phylogenetic analysis and serotyping of Vibrio splendidus-related bacteria isolated from salmon farm cleaner fish

Snorre Gulla1,2,*, Henning Sørum3, Øyvind Vågnes1,2, Duncan J. Colquhoun1,4 

1Norwegian Veterinary Institute, PO Box 750 Sentrum, 0106 Oslo, Norway
2Vaxxinova Norway AS, Kong Christian Fredriks plass 3, 5006 Bergen, Norway
3Norwegian University of Life Sciences, Department of Food Safety and Infection Biology, PO Box 8146, Dep 0033 Oslo, Norway
4University of Bergen, Department of Biology, PO BOX 7800, 5020 Bergen, Norway
*Corresponding author:

ABSTRACT: Cleaner fish, i.e. various wrasse (Labridae) species and lumpsucker Cyclopterus lumpus, are to an increasing extent used for biocontrol of the salmon louse Lepeophtheirus salmonis in European salmon farming. Although efficient de-licers, cleaner fish mortality levels in salmon farms are often high. Bacterial infections are common, and Vibrio splendidus-related strains are frequently identified during diagnostic investigations. The population structure of 112 V. splendidus-related isolates, derived primarily from wrasse species, was investigated by means of multilocus sequence analysis using 5 housekeeping genes (rpoD, ftsZ, pyrH, rpoA and atpA). Most isolates were found to be closely related to the V. splendidus type strain, yet displayed extensive genetic microdiversity. Slide agglutination testing using polyclonal rabbit antisera further indicated O-antigen variability. Intra-outbreak genetic and antigenic diversity suggests direct infection from seawater, rather than fish-to-fish transmission, as the main route of infection. The variable nature of isolates involved complicates qualified selection of representative candidate strains, e.g. for infection and vaccine trials.


KEY WORDS: Vibrio splendidus · Molecular characterisation · Multilocus sequence analysis · MLSA · Serotyping · Cleaner fish · Biocontrol · Salmon louse


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Cite this article as: Gulla S, Sørum H, Vågnes Ø, Colquhoun DJ (2015) Phylogenetic analysis and serotyping of Vibrio splendidus-related bacteria isolated from salmon farm cleaner fish. Dis Aquat Org 117:121-131. https://doi.org/10.3354/dao02938

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