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ARS Home » Northeast Area » Leetown, West Virginia » Cool and Cold Water Aquaculture Research » Research » Publications at this Location » Publication #324606
Research Project: Integrated Research to Improve On-Farm Animal Health in Salmonid Aquaculture

Location: Cool and Cold Water Aquaculture Research

Title: VIRULENCE OF Flavobacterium columnare GENOMOVARS IN RAINBOW TROUT (Oncorhynchus mykiss)

Author
item Evenhuis, Jason
item Lafrentz, Benjamin

Submitted to: Aquaculture America Conference
Publication Type: Abstract Only
Publication Acceptance Date: 1/15/2016
Publication Date: 2/26/2016
Citation: Evenhuis, J., Lafrentz, B.R. 2016. VIRULENCE OF Flavobacterium columnare GENOMOVARS IN RAINBOW TROUT (Oncorhynchus mykiss){abstract}. Aquaculture America Conference. FH2-345.

Interpretive Summary:

Technical Abstract: Flavobacterium columnare is the causative agent of columnaris disease and is responsible for significant economic losses in aquaculture. F. columnare is a Gram-negative bacterium, and five genetic types or genomovars have been described based on restriction fragment length polymorphism of the 16S rRNA gene. To date all isolates taken from disease outbreaks in rainbow trout were typed as genomovar I. Previous research has suggested that genomovar II isolates are more virulent to multiple species of fish, including rainbow trout (Oncorhynchus mykiss). Our objective was to confirm previous results and to determine the susceptibility of rainbow trout to other genomovars. The virulence of 8 genomovar I, 4 genomovar II, 3 genomovar II-B, and 5 genomovar III isolates, originating from various sources, was determined through three independent challenges in rainbow trout using an immersion challenge model. Mean cumulative percent mortality (CPM) of ~49% for genomovar I isolates, ~1% for genomovar II, <10% for the genomovar II-B and III isolates was observed. The inability of genomovar II isolates to produce mortalities in rainbow trout was unanticipated based on previous studies, but may be due to a couple of factors including rainbow trout source and water chemistry. This research demonstrates that genomovar I isolates of F. columnare are virulent toward rainbow trout but isolates from other genomovars are not as virulent. The source of fish and/or the presence of sub-optimal environment may influence the susceptibility of rainbow to different F. columnare genomovars.