Contribution of the serine protease HtrA in Escherichia coli to infection in foxes

Microb Pathog. 2019 Oct:135:103570. doi: 10.1016/j.micpath.2019.103570. Epub 2019 Jun 1.

Abstract

Escherichia coli can cause severe, acute hemorrhagic pneumonia and systemic infection in farmed foxes, raccoon dogs and minks, leading to considerable economic losses to the farmers. It is well established that the htrA-encoded serine protease HtrA is critical for bacterial growth and survival under stress, and HtrA has been determined to be a potential vaccine target. However, the roles of HtrA in E. coli pathogenesis remain unknown. In this study, we generated an htrA-deletion mutant of the E. coli protype strain HBCLE-12 that causes pneumonia in silver foxes and then evaluated the changes in bacterial physiological characteristics in the absence of HtrA. The data show that knockout of the htrA gene did not affect growth and biochemical characteristics but led to impaired virulence of the strain. Increased susceptibility to environmental stresses, impaired survival in serum, and reduced biofilm formation may contribute to the virulence attenuation of the mutant. Furthermore, the HtrA-deficient mutant was subjected to RNA-seq analysis, and 16 differentially expressed genes were determined. This study provided insight that HtrA plays a definitive role in E. coli-induced infection.

Keywords: Escherichia coli; HtrA; Pneumonia; Virulence.

MeSH terms

  • Animal Diseases / microbiology
  • Animals
  • Bacterial Proteins
  • Biofilms / growth & development
  • Cold Shock Proteins and Peptides / genetics
  • Escherichia coli / enzymology*
  • Escherichia coli / genetics*
  • Escherichia coli / growth & development
  • Escherichia coli / pathogenicity
  • Escherichia coli Infections / veterinary*
  • Foxes / microbiology*
  • Gene Expression Regulation, Bacterial
  • Gene Knockout Techniques
  • Heat-Shock Proteins / genetics*
  • Heat-Shock Proteins / metabolism*
  • Mice
  • Periplasmic Proteins / genetics*
  • Periplasmic Proteins / metabolism*
  • Pneumonia / microbiology
  • Pneumonia / veterinary
  • Sequence Deletion
  • Serine Endopeptidases / genetics*
  • Serine Endopeptidases / metabolism*
  • Stress, Physiological / genetics
  • Transcriptome
  • Virulence / genetics
  • Virulence Factors / genetics

Substances

  • Bacterial Proteins
  • Cold Shock Proteins and Peptides
  • Heat-Shock Proteins
  • Periplasmic Proteins
  • Virulence Factors
  • DegP protease
  • Serine Endopeptidases