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Research Project: Pathogen Characterization, Host Immune Response and Development of Strategies to Reduce Losses to Disease in Aquaculture

Location: Aquatic Animal Health Research

Title: Characterization of atypical Flavobacterium columnare and identification of a new genomovar

item Garcia, Julio
item Lafrentz, Benjamin
item Waldbieser, Geoffrey - Geoff
item WONG, F.S. - Merck Animal Health
item CHANG, S.F. - Merck Animal Health

Submitted to: Journal of Fish Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/5/2017
Publication Date: 6/12/2018
Citation: Garcia, J.C., LaFrentz, B.R., Waldbieser, G.C., Wong, F., Chang, S. 2018. Characterization of atypical Flavobacterium columnare and identification of a new genomovar. Journal of Fish Diseases. 41:1159-1164.

Interpretive Summary: Flavobacterium columnare is the causative agent of columnaris disease and is one of the most prevalent fish diseases worldwide. Phenotypic traits such as forming yellow adherent colonies with a rhizoid morphology on agar plates are relatively similar among isolates. However, at the genetic level, there is much diversity and five genetic types or genomovars have been established. A group of presumptive F. columnare isolates arrived to our laboratory for analysis and three presented atypical characteristics, prompting this research. Isolates were characterized by phenotypic characteristics and using genetic methods. Following growth on agar plates, isolate TI982 formed an uncharacteristic white rhizoid colony and isolate EE923 produced a diffusible brownish-red pigment. Both of these characteristics have not previously been reported in F. columnare. Upon genetic characterization, isolate CC1351 could not be assigned to one of the five established genomovars. Further analysis of isolate CC1351 resulted in a unique restriction pattern, not previously observed for F. columnare, and this isolate was assigned to a new genomovar. While the importance or significance of these atypical characteristics is not known, it is noteworthy to report these deviations from typical F. columnare traits. Additionally we describe a new genomovar, II-A, which increases the number of genomovars in F. columnare to six and further illustrates the genetic diversity in this important fish pathogen.

Technical Abstract: None.