New vaccination strategies are required for effective control of winter ulcer disease caused by emerging variant strains of Moritella viscosa in Atlantic salmon

Furevik, Anette; Tunheim, Siv Haugen; Heen, Vegar; Klevan, Are; Knutsen, Linn Emilie; Tandberg, Julia Isabel; Tingbo, Monica Gausdal

doi:10.1016/j.fsi.2023.108784

Cited by 6 publications

(1 citation statement)

References 11 publications

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“…have been isolated [ 5 , 9 ]. Despite broad immunization with polyvalent vaccines containing M. viscosa antigens, ulcerative-disease events continue to be reported, causing poor fillet quality and financial losses [ 10 , 11 ]. This suggests that undescribed bacterial species may be involved in ulcer disease pathology [ 11 ], and that they are not covered by current vaccines.…”

Section: Introductionmentioning

confidence: 99%

Comparative Genomic Analysis of a Novel Vibrio sp. Isolated from an Ulcer Disease Event in Atlantic Salmon (Salmo salar)

et al. 2023

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Ulcer diseases are a recalcitrant issue at Atlantic salmon (Salmo salar) aquaculture cage-sites across the North Atlantic region. Classical ulcerative outbreaks (also called winter ulcer disease) refer to a skin infection caused by Moritella viscosa. However, several bacterial species are frequently isolated from ulcer disease events, and it is unclear if other undescribed pathogens are implicated in ulcer disease in Atlantic salmon. Although different polyvalent vaccines are used against M. viscosa, ulcerative outbreaks are continuously reported in Atlantic salmon in Canada. This study analyzed the phenotypical and genomic characteristics of Vibrio sp. J383 isolated from internal organs of vaccinated farmed Atlantic salmon displaying clinical signs of ulcer disease. Infection assays conducted on vaccinated farmed Atlantic salmon and revealed that Vibrio sp. J383 causes a low level of mortalities when administered intracelomic at doses ranging from 107–108 CFU/dose. Vibrio sp. J383 persisted in the blood of infected fish for at least 8 weeks at 10 and 12 °C. Clinical signs of this disease were greatest 12 °C, but no mortality and bacteremia were observed at 16 °C. The Vibrio sp. J383 genome (5,902,734 bp) has two chromosomes of 3,633,265 bp and 2,068,312 bp, respectively, and one large plasmid of 201,166 bp. Phylogenetic and comparative analyses indicated that Vibrio sp. J383 is related to V. splendidus, with 93% identity. Furthermore, the phenotypic analysis showed that there were significant differences between Vibrio sp. J383 and other Vibrio spp, suggesting J383 is a novel Vibrio species adapted to cold temperatures.

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