Secreted peptidases contribute to virulence of fish pathogen Flavobacterium columnare

Nicole C Thunes; Haitham H Mohammed; Jason P Evenhuis; Ryan S Lipscomb; David Pérez-Pascual; Rebecca J Stevick; Clayton Birkett; Rachel A Conrad; Jean-Marc Ghigo; Mark J McBride

doi:10.3389/fcimb.2023.1093393

Secreted peptidases contribute to virulence of fish pathogen Flavobacterium columnare

Front Cell Infect Microbiol. 2023 Feb 3:13:1093393. doi: 10.3389/fcimb.2023.1093393. eCollection 2023.

Authors

Affiliations

¹ Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, United States.
² Department of Rangeland, Wildlife and Fisheries Management, Texas A&M University, College Station, TX, United States.
³ National Center for Cool and Cold Water Aquaculture, Agricultural Research Service, United States Department of Agriculture, Kearneysville, WV, United States.
⁴ Institut Pasteur, Université de Paris-Cité, Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche (UMR) 6047, Genetics of Biofilms Laboratory, Paris, France.

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, and control options such as vaccines are limited. 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 ΔgldN and ΔporV, exhibit strong defects in secreted proteolytic activity. The F. columnare genome has many peptidase-encoding genes that 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 TspA exhibited decreased virulence in rainbow trout fry, suggesting that peptidases contribute to F. columnare virulence.

Keywords: fish pathogen; flavobacterium; gene deletion; protease; type IX secretion system (T9SS).

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Animals
Fish Diseases* / microbiology
Flavobacteriaceae Infections* / microbiology
Flavobacterium
Oncorhynchus mykiss*
Peptide Hydrolases / metabolism
Virulence
Virulence Factors / metabolism
Zebrafish

Substances

Peptide Hydrolases
Virulence Factors

Supplementary concepts

Flavobacterium columnare

Grants and funding

This work was funded in part by United States Department of Agriculture-ARS CRIS projects 8082-32000-006-00-D and 5090-31320-004-00D and by cooperative agreements 5090-31320-004-03S and 58-5090-1-022, and by grant NA18OAR4170097, project R/SFA-20 from the University of Wisconsin Sea Grant Institute under grants from the National Sea Grant College Program, National Oceanic and Atmospheric Administration, U.S. Department of Commerce, and the State of Wisconsin. JMG, DPP and RS were funded by the French government’s Investissement d’Avenir Program, Laboratoire d’Excellence “Integrative Biology of Emerging Infectious Diseases” (grant ANR-10-LABX-62-IBEID) and by an Institut Carnot Pasteur MS fellowship. The views contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. Government. Mention of trade name, proprietary product, or specific equipment does not constitute a guarantee or warranty by the USDA and does not imply its approval to the exclusion of other products that may be suitable.