Poster Presentation The 2nd Prato Conference on the Pathogenesis of Bacterial Diseases of Animals 2012

Aeromonas salmonicida subsp salmonicida genomic diversity analysis: identification of two novel genetic elements potentially related to virulence     (#68)

Katherine H. Tanaka 1 , Mélanie V. Trudel 1 , Brian Boyle 1 , Francis Brochu 1 , Laurence Nadeau 1 , Éric Jubinville 1 , Nicolas Derome 1 2 , Michel Frenette 3 4 , Steve J. Charette 1 3
  1. Institut de biologie intégrative et des systèmes (IBIS), Université Laval, Québec, QC, Canada
  2. Département de biologie, Université Laval, Québec, QC, Canada
  3. Département de biochimie, microbiologie et bio-informatique, Université Laval, Québec, QC, Canada
  4. Groupe de recherche en écologie buccale (GREB), Université Laval, Québec, QC, Canada

Aeromonas salmonicida subsp. salmonicida is the causative agent of furunculosis, which causes septicaemia and necrosis in salmonids4 . Although furunculosis is an important issue in aquaculture, the genomic diversity among strains of this bacterium remains to be analyzed in details. Previous studies, focusing on plasmid composition and PFGE patterns, showed that “typical” A. salmonicida strains are genetically homogenous1 3. However, it does not explain the variation in virulence among strains. A. salmonicida “typical” strain A449 have been fully sequenced in 20085. Unfortunately, this strain is not virulent when assayed in the infection model of the alternative host Dictyostelium discoideum amoeba2. Thus, sequencing of highly virulent A. salmomicida strains should allow the identification of new genetic elements associated with the pathogenesis of these bacteria. Whole genome sequencing of two virulent strains, 01-B526 (Province of Quebec, Canada) and JF2267 (Switzerland), was performed by Roche/454 pyrosequencing method. A supplementary 51 kb element was identified in strain 01-B526. This phage-like element, hence named phiAS526, may contain potential virulence factors. At least one segment of phiAS526 is widespread among A. salmonicida strains while another portion seems specifically found in strains in Province of Québec. Moreover, an additional 6 kb element was present in strain JF2267. This element contains genes related to pilus assembly. Thus, next generation sequencing brings light on A. salmonicida genetic diversity and quickens research on this ichtyopathogen as demonstrated by the discovery of two new genetic elements potentially involved in bacterial virulence in the current study.

  1. Belland, R. J. & T. J. Trust (1989) Aeromonas salmonicida plasmids: plasmid-directed synthesis of protelns in vitro and in Escherichia coli minicells. J Gen Microbiol, 135, 513-524.
  2. Daher, R. K., G. Filion, S. G. Tan, S. Dallaire-Dufresne, V. E. Paquet & S. J. Charette (2011) Alteration of virulence factors and rearrangement of pAsa5 plasmid caused by the growth of Aeromonas salmonicida in stressful conditions. Vet Microbiol, 152, 353-360.
  3. Hanninen, M. L. & V. HirvelaKoski (1997) Pulsed-field gel electrophoresis in the study of mesophilic and psychrophilic Aeromonas spp. Journal of Applied Microbiology, 83, 493-498.
  4. Hiney, M. & G. Olivier. 1999. Furunculosis (Aeromonas salmonicida). In Fish Diseases and Disorders III: Viral, Bacterial and Fungal Infections, eds. P. Woo & D. Bruno, 341-425. Oxford: CAB Publishing.
  5. Reith, M. E., R. K. Singh, B. Curtis, J. M. Boyd, A. Bouevitch, J. Kimball, J. Munholland, C. Murphy, D. Sarty, J. Williams, J. H. Nash, S. C. Johnson & L. L. Brown (2008) The genome of Aeromonas salmonicida subsp. salmonicida A449: insights into the evolution of a fish pathogen. BMC Genomics, 9, 427.