Submitted to: European Association of Fish Pathologists
Publication Type: Abstract Only
Publication Acceptance Date: 4/16/2007
Publication Date: 9/17/2007
Citation: Shoemaker, C.A., Olivares-Fuster, O., Arias, C., Klesius, P.H., Evans, J.J. 2007. Genomovar influences flavobacterium columnare mortality in channel catfish (Ictalurus punctatus). page 133. European Association of Fish Pathologists. 13th EAFP International Conference on 'Disease of Fish and Shellfish' 17th-21st September, 2007 Grado, Italy. Interpretive Summary:
Technical Abstract: Genetic diversity has been documented and confirmed in Flavobacterium columnare, causal agent of columnaris disease. This aquatic bacterium is pathogenic to many species of freshwater fish throughout the world. The United States channel catfish (Ictalurus punctatus) aquaculture industry is severely impacted by columnaris disease with losses estimated at $40-50 million, annually. The majority of the F. columnare isolates recovered from diseased channel catfish by diagnostic laboratories in the U.S. belonged to either genomovar I or genomovar II. The objective of the present study was to determine if differences existed in the ability of these genomovars to induce mortality in channel catfish. Single strand conformation polymorphism analysis (SSCP) was used to ascribe the isolates used in this study to the appropriate genomovar. Immersion challenge experiments (15 minute immersion exposure to about 5 X 105 CFU/ml) were carried out to assess virulence of genomovar I and II isolates to fry and fingerling channel catfish. The results demonstrated genomovar II isolates were significantly (P < 0.05) more virulent in channel catfish fry (92 – 100% mortality) than genomovar I isolates (0 - 46% mortality). Genomovar effect in fingerling channel catfish was also significant (P < 0.05) with genomovar II resulting in increased mortality (74.7% versus 30.2%). The study also correlated (r2=0.73) in vivo adhesion (adherence to fry) of the genetically characterized F. columnare used in this study to increased mortality in the challenged catfish.