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ARS Home » Northeast Area » Leetown, West Virginia » Cool and Cold Water Aquaculture Research » Research » Publications at this Location » Publication #399629
Research Project: Improving Salmonid Health through Breeding, Vaccination and Microbiome Modulation

Location: Cool and Cold Water Aquaculture Research

Title: Secreted peptidases contribute to virulence of fish pathogen Flavobacterium columnare

Author
item THUNES, NICOLE - University Of Wisconsin
item MOHAMMED, HAITHAM - University Of Wisconsin
item Evenhuis, Jason
item Lipscomb, Ryan
item PEREZ-PASCUAL, DAVID - Institut Pasteur - France
item STEVICK, REBECCA - Institut Pasteur - France
item Birkett, Clayton
item CONRAD, RACHEL - University Of Wisconsin
item GHIGO, JEAN-MARC - Institut Pasteur - France
item MCBRIDE, MARK - University Of Wisconsin

Submitted to: Frontiers in Cellular and Infection Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/18/2023
Publication Date: 2/3/2023
Citation: Thunes, N.C., Mohammed, H.H., Evenhuis, J., Lipscomb, R.S., Perez-Pascual, D., Stevick, R.J., Birkett, C., Conrad, R.A., Ghigo, J., Mcbride, M.J. 2023. Secreted peptidases contribute to virulence of fish pathogen Flavobacterium columnare. Frontiers in Cellular and Infection Microbiology. 13. Article:1093393. https://doi.org/10.3389/fcimb.2023.1093393.
DOI: https://doi.org/10.3389/fcimb.2023.1093393

Interpretive Summary: Flavobacterium columnare is a major problem for sustainable freshwater aquaculture and control options are limited. Understanding virulence mechanisms of F. columnare may lead to better treatment options and potential vaccines. A series of mutant Flavobacterium columnare stains were made targeting peptidase genes. Mutant strains lacking between one and ten genes were generated and assessed for virulence in rainbow trout and zebrafish. Reduction of virulence actively against rainbow trout was achieved in mutants with 10 gene mutations and the single mutation, C6N29_08680, but in no other mutant combination tested. These results indicate differences in virulence pathways between rainbow trout and zebrafish and the role of peptidases in virulence. Peptidases acting as virulence factors are candidates for potential vaccine targets and other control measures.

Technical Abstract: Flavobacterium columnare causes columnaris disease in freshwater fish in both natural and aquaculture settings. This disease is often lethal, especially when fish population density is high. Control options are limited and adequate vaccines are lacking. Virulence mechanisms of F. columnare are poorly understood. The type IX secretion system (T9SS) is required for F. columnare virulence, but secreted virulence factors have not been fully identified. Many T9SS-secreted proteins are predicted peptidases, and peptidases are common virulence factors of other pathogens. T9SS-deficient mutants, such as 'gldN and 'porV, exhibit defects in secreted proteolytic activity. The F. columnare genome has many peptidase-encoding genes, some of which may be redundant. These peptidases may be involved in nutrient acquisition and/or virulence. Mutants lacking individual peptidase-encoding genes, or lacking up to ten peptidase-encoding genes, were constructed and examined for extracellular proteolytic activity, for growth defects, and for virulence in zebrafish and rainbow trout. Most of the mutants retained virulence, but a mutant lacking 10 peptidases, and a mutant lacking the single peptidase C6N29_08680, exhibited decreased virulence in rainbow trout fry, suggesting that peptidases contribute to F. columnare virulence.