Flavobacterium columnare protease knockout shows potential for vaccine development against columnaris disease
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Flavobacterium columnare is a gram negative, slender rod bacterium that primarily infects salmonids in hot or cold water systems. Columnaris disease is symptomatically represented by long “straw-like” colonies on mucosal surfaces of fish species. Fish infection trials have been conducted to understand infectivity however, the cause of pathogenesis is still under investigation. These strictly aerobic bacteria require a unique apparatus called the Type Nine Secretion System (T9SS) to infect fish. The T9SS is involved in both secretion and motility. Essential T9SS genes characterized include porV and gldN genes which have been shown to be essential for virulence of F. columnare in fish. The porV and gldN effects on the T9SS have been studied extensively to understand their contributions pathogenesis of columnaris disease. The aim of the current study is to understand specific cargo of the T9SS and its effect on virulence. Using a zebrafish mortality assay and silver stain gel techniques, we examined the effect of spent media (containing proteins secreted by the bacterium) from both wild type F. columnare and strains with knockouts in genes coding for multiple proteases thought to be secreted by the T9SS. Results suggest the strains lacking specific metalloproteases appear to be reduced in virulence, while several other protease knockouts show wild-type virulence. Continued genetic manipulation of F. columnare strains and virulence testing in our zebrafish model should shed more light on the mechanisms by which F. columnare causes disease in fish and may lead to the identification of vaccine candidates.
Dr. David Hunnicutt, Biology
undergraduate, research, collaboration, biology, bacterium, Columnaris diseas, vaccine
Fox, Austin, "Flavobacterium columnare protease knockout shows potential for vaccine development against columnaris disease" (2021). Student Presentations. 28.