Identification of a large repetitive RTX immunogen in a highly virulent Rodentibacter heylii strain

Microbes Infect. 2021 Mar-Apr;23(2-3):104771. doi: 10.1016/j.micinf.2020.10.007. Epub 2020 Oct 23.


Rodentibacter (R.) heylii is frequently detected in laboratory rodents. Repeats in toxin (RTX) toxins are considered important virulence factors of this major murine pathogen. We evaluated the virulence of a R.heylii strain negative for all known RTX toxin genes and Muribacter (M.) muris, a commensal in mice, in experimental infections of C57BL/6 and BALB/c mice. Experimental intranasal infection with 108 CFU of the pnxI-, pnxII- and pnxIII- R. heylii strain resulted in 75% and 100% mortality in C57BL/6 and BALB/c mice, respectively. In early losses, multiple internal organs were infected and purulent bronchopneumonia was the main pathology. Intranasal application of M. muris did not result in mortality or severe weight loss. Immunoproteomics led to the identification of a surface-associated and specific immunogen, which was designated as R. heylii immunogen A (RhiA) and which was exclusively recognised by sera obtained from mice infected with this R. heylii pathotype. RhiA is a 262.6 kDa large protein containing long imperfect tandem repeats and C-terminal RTX consensus sequences. Immunohistochemical analysis confirmed that this R.heylii pathotype expresses RhiA in the lower respiratory tract. In summary, this study describes a specific immunogen in a virulent R. heylii, strain which is an excellent antigen for pathotype-specific serological screenings and which might carry out RTX-related functions.

Keywords: Bronchopneumonia; Immunoproteomics; Muribacter muris; Pasteurella pneumotropica; RTX toxins; Rodentibacter pneumotropicus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacterial Proteins / immunology*
  • Bacterial Toxins / genetics
  • Bacterial Toxins / immunology
  • Consensus Sequence
  • Male
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Pasteurellaceae / chemistry
  • Pasteurellaceae / genetics
  • Pasteurellaceae / immunology*
  • Pasteurellaceae / pathogenicity
  • Pasteurellaceae Infections / microbiology
  • Pasteurellaceae Infections / mortality
  • Pasteurellaceae Infections / veterinary*
  • Protein Domains
  • Tandem Repeat Sequences
  • Virulence
  • Virulence Factors / chemistry
  • Virulence Factors / genetics
  • Virulence Factors / immunology


  • Bacterial Proteins
  • Bacterial Toxins
  • Virulence Factors

Supplementary concepts

  • Rodentibacter heylii