The capsular polysaccharide (CPS) of Streptococcus suis defines various serotypes based on its composition and structure. Though serotype switching has been suggested to occur between S. suis strains, its impact on pathogenicity and virulence remains unknown. Herein, we experimentally generated S. suis serotype-switched mutants from a serotype 2 strain that express the serotype 3, 4, 7, 8, 9, or 14 CPS. The effects of serotype switching were then investigated with regards to classical properties conferred by presence of the serotype 2 CPS, including adhesion to/invasion of epithelial cells, resistance to phagocytosis by macrophages, killing by whole blood, dendritic cell-derived pro-inflammatory mediator production and virulence using mouse and porcine infection models. Results demonstrated that these properties on host cell interactions were differentially modulated depending on the switched serotypes, although some different mutations other than loci of CPS-related genes were found in each the serotype-switched mutant. Among the serotype-switched mutants, the mutant expressing the serotype 8 CPS was hyper-virulent, whereas mutants expressing the serotype 3 or 4 CPSs had reduced virulence. By contrast, switching to serotype 7, 9, or 14 CPSs had little to no effect. These findings suggest that serotype switching can drastically alter S. suis virulence and host cell interactions.
disease, Bacterial, virulence, serotype, capsular polysaccharide, Streptococcus suis, animal health
NCBI PubMed ID: 33753801Publication DOI: 10.1038/s41598-021-85882-3Journal NLM ID: 101563288Publisher: London: Nature Publishing Group
Correspondence: mokura@affrc.go.jp; mariela.segura@umontreal.ca; marcelo.gottshcalk@umontreal.ca
Institutions: The United Graduate School of Veterinary Sciences, Gifu University, Gifu, Gifu, Japan, Division of Bacterial and Parasitic Diseases, National Institute of Animal Health, National Agriculture and Food Research Organization, Tsukuba, Japan, Saint-Hyacinthe Research and Development Centre, Agriculture and Agri-Food Canada, Saint-Hyacinthe, QC, Canada, Faculty of Veterinary Medicine, University of Montreal, Saint-Hyacinthe, QC, Canada, Division of Pathology and Pathophysiology, National Institute of Animal Health, National Agriculture and Food Research Organization, Tsukuba, Japan, Department of Veterinary Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Izumisano, Osaka, Japan, Microbial Genomics and Ecology, Office of Industry-Academia-Government and Community Collaboration, Hiroshima University, Hiroshima, Japan, Scientific and Technological Bioresource Nucleus, Universidad de La Frontera, Temuco, Chile, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan
Methods: 13C NMR, 1H NMR, NMR-2D, PCR, ELISA, genetic methods, serotyping, bactericidal assays, TEM, phagocytosis assay, genome sequencing
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