Serological diversity in Flavobacterium psychrophilum: A critical update using isolates retrieved from Chilean salmon farms

• Published in: Journal of Fish Diseases
• Main Authors: Avendaño-Herrera, Rubén E., Tapia-Cammas, Diana, Duchaud, Éric, Irgang, Rute
• Other Authors: Universidad Andrés Bello Santiago (UNAB), Interdisciplinary Center for Aquaculture Research, Universidad de Concepción = University of Concepción Chile (UdeC), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Virologie et Immunologie Moléculaires (VIM (UR 0892)), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Paris-Saclay-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Agencia de Innovación y Desarrollo de Andalucía, IDEA 15110027, This study was supported by the FONDAP 15110027 grant awarded by the Agencia Nacional de Investigaci?n y Desarrollo (ANID, Chile). The authors are grateful to the collaboration of the veterinary teams from the different salmonid farms. Special thanks are expressed to Professor Jean-Francois Bernardet for his aid.
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2020
• Subjects: Chilean salmon farms; Flavobacterium psychrophilum; serological diversity; serotype PCR; Updated serotyping for Chilean F. psychrophilum serological diversity; [SDV]Life Sciences [q-bio]; Atlantic salmon; Salmo salar
• Online Access: https://hal.science/hal-02938415; https://hal.science/hal-02938415/document; https://hal.science/hal-02938415/file/Duchaud.pdf; https://doi.org/10.1111/jfd.13199

International audience Chile is currently the second largest producer of farmed salmon worldwide, but Flavobacterium psychrophilum, as one of the most detrimental pathogens, is responsible for major losses during the freshwater culturing step in salmonid fish farms. An antigenic study conducted 10 years ago reported four serological groups using 20 F. psychrophilum Chilean strains. To reduce disease outbreaks and to develop vaccine candidates, antigenic knowledge needs to be regularly updated using a significant number of additional recent F. psychrophilum isolates. The present study aimed at investigating the serological diversity of 118 F. psychrophilum isolates collected between 2006 and 2018 from farmed Atlantic salmon (Salmo salar), rainbow trout (Oncorhynchus mykiss) and coho salmon (Oncorhynchus kisutch). The current study supports an expansion of the known antigenic groups in Chile from 4 to 14. However, the use of the slide-agglutination technique for serotyping is costly, is labour-intensive and requires significant technical expertise. Addressing these points, the mPCR-based procedure was a very useful tool for serotyping the collected Chilean F. psychrophilum isolates. This technique revealed the presence of diverse mPCR serotypes (i.e. types 0, 1, 2 and 4). Therefore, mPCR should be employed to select the bacterial strain(s) for vaccine development and to conduct follow-up, selective breeding or epidemiological surveillance in Chilean fish farms. Given the presented findings, changes to Chilean fish-farming practices are vital for ensuring the continued productivity and well-being of farmed salmonids.