Effect of extracellular products of Tenacibaculum maritimum in Atlantic salmon, Salmo salar L

• Published in: Journal of Fish Diseases
• Main Authors: van Gelderen, R, Carson, J, Nowak, BF
• Format: Article in Journal/Newspaper
• Language: English
• Published: Blackwell Publishing Ltd 2009
• Subjects: Agricultural and Veterinary Sciences; Fisheries Sciences; Fish Pests and Diseases; Ferguson; Morrison; Atlantic salmon; Salmo salar
• Online Access: https://doi.org/10.1111/j.1365-2761.2009.01032.x; http://www.ncbi.nlm.nih.gov/pubmed/19531097; http://ecite.utas.edu.au/60143

Keywords: Atlantic salmon, extracellular products,LD50, Tenacibaculum maritimum, toxins.Tenacibaculum maritimum (formerly Flexibactermaritimus) is a well-known pathogen in a numberof cultured fish species worldwide (Wakabayashi,Hikida & Masumura 1986; Alsina & Blanch 1993;Chen, Henry-Ford & Groff 1995; Handlinger,Soltani & Percival 1997; Ostland, LaTrace,Morrison & Ferguson 1999). It is a marinebacterium that causes necrotic lesions on the body,head, fins and gills, with erosive lesions on theexternal surface as the prominent clinical sign(Carson, McCosh & Schmidtke 1992). In Australia,the main species affected are Atlantic salmon,Salmo salar L., and rainbow trout, Oncorhynchusmykiss (Walbaum), in sea-cage culture in Tasmania(Handlinger et al. 1997). Experimental investigationinto the pathogenesis of T. maritimumshowed that challenge at higher doses (c. 1 108 cells mL)1) had an acute lethal effect onAtlantic salmon (van Gelderen 2007). Mortalitiesoccurred within days and the clinical sign was thedisintegration of the epithelium. In addition, a lackof an inflammatory response is characteristic ofearly flexibacteriosis lesions. Handlinger et al.(1997) suggested that this was the result of powerfulexotoxins that prevent a host response. Thesefindings pointed to a possible role of toxins in thepathogenicity of T. maritimum in Atlantic salmon.Effects of T. maritimum toxins have beenexplored in red and black sea bream, Pagrus major(Temminck and Schlegel), and Acanthopagrus schlegeli(Bleeker) (Baxa, Kawai & Kusuda 1988). Inboth fish species, extracellular products (ECP)showed insignificant in vitro activity; however, thisdid not correspond with the toxic effects observedin vivo with ECP recording the lowest LD50. Baxaet al. (1988) did indicate that the pathogenicity ofT. maritimum in black and red sea bream may beascribed in part to ECP. The current studyinvestigated ECP toxicity in vivo to observe directeffects rather than in vitro activity of differenttoxins. Further, this study provides the first observationsof T. maritimum ECP toxicity in Atlanticsalmon.