Characterizing the bacterial fish pathogen Flavobacterium columnare, and some factors affecting its pathogenicity

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dc.contributor.author Kunttu, Heidi
dc.date.accessioned 2010-05-03T06:34:41Z
dc.date.available 2010-05-03T06:34:41Z
dc.date.issued 2010
dc.identifier.isbn 978-951-39-3867-3
dc.identifier.uri http://urn.fi/URN:ISBN:978-951-39-3867-3
dc.identifier.uri http://hdl.handle.net/123456789/23323
dc.description.abstract Flavobacterium columnare is a bacterial pathogen of fresh water fish causing lethal columnaris disease worldwide. At Finnish fish farms, columnaris disease has occurred since the early 1980s, and is a serious problem in salmonid farming in Finland. Currently, the only effective treatment is with antibiotics. Factors related to the pathogenicity of F. columnare, transmission of columnaris disease and the immunity of salmonids to columnaris infections are poorly known. F. columnare strains isolated from Finnish fish farms were characterized geno- and phenotypically, virulence and transmission experiments were conducted, and the efficacy of two immunostimulants against columnaris infections in rainbow trout (Oncorhynchus mykiss Walbaum) fingerlings was evaluated. Finnish F. columnare strains constituted a genetically homogeneous group that differed from strains isolated from other parts of the world and tolerated narrower pH and salinity ranges than F. columnare type strain (NCIMB 2248T). Finnish strains could be divided into seven genetic groups, which can co-occur during the same outbreak at fish farms. Among the genetic groups, four colony types were formed. Formation of rhizoid colonies is suggested to be a prerequisite for virulence of F. columnare. Colony types may have a role in the infection process and persistence of F. columnare at fish farms. The bacterium was able to survive in fresh water and also as a saprophyte, and to use saprophytism as a transmission strategy. These properties, together with co-occurrence of different genetic groups, may promote the continuous nature of outbreaks at fish farms and lead to development of highly virulent F. columnare strains. Immunostimulation was effective in boosting innate immune defence parameters of rainbow trout, but was inefficient in protecting fish against F. columnare infections. This suggests that antibody-mediated immunity is also essential in protecting fish from columnaris disease. en
dc.language.iso eng
dc.publisher University of Jyväskylä
dc.relation.ispartofseries Jyväskylä studies in biological and environmental science;1456-9701 ;206.
dc.relation.isversionof ISBN 978-951-39-3853-6
dc.subject.other kalapatogeenit
dc.subject.other saprofytia
dc.subject.other immunostimulaatio
dc.subject.other virulenssi
dc.subject.other columnaris disease
dc.subject.other fish pathogens
dc.subject.other saprophytism
dc.subject.other immunostimulation
dc.subject.other virulence
dc.subject.other bacterial colony types
dc.title Characterizing the bacterial fish pathogen Flavobacterium columnare, and some factors affecting its pathogenicity
dc.type Diss. fi
dc.identifier.urn URN:ISBN:978-951-39-3867-3
dc.subject.ysa taudinaiheuttajat
dc.subject.kota 118
dc.type.dcmitype Text en
dc.type.ontasot Väitöskirja fi
dc.type.ontasot Doctoral dissertation en
dc.contributor.tiedekunta Matemaattis-luonnontieteellinen tiedekunta fi
dc.contributor.tiedekunta Faculty of Mathematics and Science en
dc.contributor.yliopisto University of Jyväskylä en
dc.contributor.yliopisto Jyväskylän yliopisto fi

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