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Diseases of Aquatic Organisms

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DAO 155:7-19 (2023)  -  DOI:

Exploring Yersinia ruckeri (O1 Biotype 2) infection in three early life-stages of rainbow trout

Ava Waine1,2,*, Ioanna Katsiadaki1, Marion Sebire1, Hannah Tidbury1

1Cefas Weymouth Laboratory, The Nothe, Barrack Road, Weymouth, Dorset DT4 8UB, UK
2School of Natural and Environmental Sciences, Newcastle University, NE1 7RU, UK
*Corresponding author:

ABSTRACT: Enteric redmouth disease (ERM) caused by the enterobacterium Yersinia ruckeri poses a significant threat to salmonid aquaculture globally. Despite decades of experimental infection studies, key knowledge gaps remain regarding the onset of disease susceptibility and mechanisms of immunity during early developmental stages, undermining disease management efforts in all susceptible life-stages. In this study, a series of immersion challenges were conducted, challenging and re-challenging rainbow trout Oncorhynchus mykiss (Walbaum) at 7, 14 and 51 d post-hatch (dph; mean weights = 0.085, 0.1 and 2.0 g respectively) to high concentrations (1.72 × 107-1.1 × 108 CFU) of Y. ruckeri at 15°C. This study indicates the hitherto unknown initial point of susceptibility to infection as the time of first ingestion of exogenous food (14 dph), and shows that individuals surviving primary challenge at 14 dph are significantly more likely to survive re-challenge at 51 dph compared with naive individuals (hazard ratio = 1.446, p = 0.032). Other key findings include large variation in mortality between different development-stages, from 21.1% at 14 dph to 81.2% at 51 dph, and novel age-dependent symptoms not reported previously. Results from this study enhance our understanding of ERM in juvenile rainbow trout and inform the development of improved aquatic animal health management strategies, thereby contributing to the productivity and sustainability of salmonid aquaculture into the future.

KEY WORDS: Salmonid · Susceptibility · Immunity · Aquaculture disease management · Enteric redmouth disease · ERM · Yersiniosis

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Cite this article as: Waine A, Katsiadaki I, Sebire M, Tidbury H (2023) Exploring Yersinia ruckeri (O1 Biotype 2) infection in three early life-stages of rainbow trout. Dis Aquat Org 155:7-19.

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