10–12 Sept 2025
Kaiserin-Friedrich-Stiftung, Berlin
Europe/Berlin timezone

Genomic and virulence insights of Western European Aeromonas salmonicida subsp. salmonicida and development of Galleria mellonella infection assay

12 Sept 2025, 15:15
15m
Seminar Room

Seminar Room

Oral presentation Veterinary Bacteriology, Mycology and Virology Omics techniques

Speaker

Ms Salomé Desmecht (Veterinary Bacteriology Laboratory, Department of Infectious and Parasitic Diseases, Fundamental and Applied Research for Animals & Health (FARAH), Faculty of Veterinary Medicine, University of Liège, Liège, Belgium)

Description

Aeromonas salmonicida subsp. salmonicida is the etiological agent of furunculosis, a fish disease highly aggressive for salmonids and responsible for significant economic losses in aquaculture worldwide. This study aimed to explore genomic and antimicrobial resistance traits of Western European A. salmonicida subsp. salmonicida strains and to develop an adapted Galleria mellonella infection model to assess the pathogenic potential of this psychrophilic subspecies. Three strains isolated from salmonids displaying symptoms of furunculosis were tested against a panel of antibiotics and sequenced to characterize their genome. Virulence was evaluated in G. mellonella larvae using bacterial doses ranging from 101 to 106 CFU/larva. Two isolates exhibited multidrug resistance to antibiotics commonly used against furunculosis. Although closely related to the reference strain A449, genomic analyses revealed multiple plasmids known to encode antibiotic resistance genes. Virulence assays demonstrated that this subspecies is lethal at doses as low as 101 CFU/larva, and that a fully functional Type III Secretion System (T3SS) is not essential for the infection of G. mellonella, likely due to the presence of other virulence factors in T3SS-deficient strains. These findings enhance the genomic characterization of European A. salmonicida subsp. salmonicida and validate the use of Galleria mellonella larvae as a relevant alternative infection model for studying this psychrophilic subspecies.

Keywords

European Aeromonas salmonicida; virulence; Galleria mellonella; antimicrobial resistance; mobile genetic elements

Registration ID ECVM25-47
Professional Status of the submitter, who is also the speaker PhD Student

Author

Ms Salomé Desmecht (Veterinary Bacteriology Laboratory, Department of Infectious and Parasitic Diseases, Fundamental and Applied Research for Animals & Health (FARAH), Faculty of Veterinary Medicine, University of Liège, Liège, Belgium)

Co-authors

Mr Fabrice Touzain (Viral Genetics and Biosafety Unit, Ploufragan-Plouzané-Niort laboratory, ANSES, Ploufragan, France) Thibaut Olivier (Department of Pathology, Fundamental and Applied Research for Animals & Health (FARAH), Faculty of Veterinary Medicine, University of Liège, Liège, Belgium) Ms Céline Antoine (Veterinary Bacteriology Laboratory, Department of Infectious and Parasitic Diseases, Fundamental and Applied Research for Animals & Health (FARAH), Faculty of Veterinary Medicine, University of Liège, Liège, Belgium) Ms Véronique Beven (Viral Genetics and Biosafety Unit, Ploufragan-Plouzané-Niort laboratory, ANSES, Ploufragan, France) Ms Cécile Meex (Department of Clinical Microbiology, University Hospital of Liège, Liège, Belgium) Mr François Lieffrig (Fish pathology laboratory, CER groupe, Marche-en-Famenne, Belgium) Mr Steve J. Charette (Institut de Biologie Intégrative et des Systèmes (IBIS), Laval University, Quebec, Canada) Mr Damien Thiry (Veterinary Bacteriology Laboratory, Department of Infectious and Parasitic Diseases, Fundamental and Applied Research for Animals & Health (FARAH), Faculty of Veterinary Medicine, University of Liège, Liège, Belgium)

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