University of Leicester
Browse
2020 Zbinden fcimb.pdf (2.49 MB)

Pathogenic Differences of Type 1 Restriction-Modification Allele Variants in Experimental Listeria monocytogenes Meningitis

Download (2.49 MB)
journal contribution
posted on 2020-11-27, 16:55 authored by FR Zbinden, M De Ste Croix, D Grandgirard, RD Haigh, I Vacca, R Zamudio, ECA Goodall, R Stephan, MR Oggioni, SL Leib
Background: L. monocytogenes meningoencephalitis has a mortality rate of up to 50% and neurofunctional sequelae are common. Type I restriction-modification systems (RMS) are capable of adding methyl groups to the host genome. Some contain multiple sequence recognition (hsdS) genes that recombine, resulting in distinct DNA methylation patterns and patterns of gene expression. These phenotypic switches have been linked to virulence and have recently been discovered in multiple clonal complexes of L. monocytogenes. In the present study, we investigated the significant of RMS on L. monocytogenes virulence during the acute phase of experimental meningitis.

Methods: L. monocytogenes strains containing RMS systems were identified, and purified clones enriched for single hsdS alleles were isolated. In vivo, 11-day old Wistar rats were infected with an inoculum containing (a) one of 4 single RMS allele variants (A, B, C, D) treated with amoxicillin (AMX 50 mg/kg/dosis, q8h), (b) a mixture of all 4 variants with or without AMX treatment, or (c) different mixtures of 2 RMS allele variants. At selected time points after infection, clinical and inflammatory parameters, bacterial titers and brain damage were determined. Changes in the relative frequency of the occurring RMS alleles in the inoculum and in CSF or cerebellum of infected animals were analyzed by capillary electrophoresis.

Results: We have identified a phase variable RMS locus within L. monocytogenes CC4 and generated stocks that stably expressed each of the possible hsdS genes within that loci. Generation of these allele variants (A, B, C, D) allowed us to determine the methylation pattern associated with each hsdS through SMRT sequencing. In vivo infections with these single allele variants revealed differences in disease severity in that C induced the worst clinical outcome and more pronounced hippocampal apoptosis; D showed the most pronounced weight loss and the highest bacterial titer in the cerebellum. A caused the least severe disease.

Conclusion: We identified that L. monocytogenes expressing hsdS (A) causes less damage than when other hsdS genes are expressed. While expression of hsdSC and D worsened the outcome in L. monocytogenes meningitis. We also demonstrate a competitive advantage of variants C and B over variant A in this model. Phenotypical switching may therefore represent a mechanism of virulence regulation during the acute phase of CNS infections with L. monocytogenes.

History

Citation

Front. Cell. Infect. Microbiol., 30 October 2020 | https://doi.org/10.3389/fcimb.2020.590657

Author affiliation

Department of Genetics and Genome Biology

Version

  • VoR (Version of Record)

Published in

Frontiers in Cellular and Infection Microbiology

Volume

10

Pagination

590657

Publisher

Frontiers Media SA

issn

2235-2988

eissn

2235-2988

Acceptance date

2020-09-25

Copyright date

2020

Available date

2020-10-30

Spatial coverage

Switzerland

Language

eng

Usage metrics

    University of Leicester Publications

    Categories

    No categories selected

    Licence

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC