Clonal expansion of a virulent Streptococcus suis serotype 9 lineage distinguishable from carriage subpopulations

Niels Willemse, Kees C.H. van der Ark, Norbert Stockhofe-Zurwieden, Hilde Smith, Daisy I. Picavet, Conny van Solt-Smits, Henk J. Wisselink, Constance Schultsz*, Astrid de Greeff

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Streptococcus suis is a porcine pathogen, causing severe invasive infections. S. suis serotype 9 is increasingly causing disease in Dutch and Chinese pig herds, but it is unknown whether all serotype 9 isolates are equally virulent and markers that can identify virulent strains are not available. Therefore, discrimination between virulent isolates and carriage isolates typically not associated with disease, is currently not possible. We collected tonsillar S. suis isolates from 6 herds not previously diagnosed with S. suis infections, and clinical S. suis isolates of previously diseased pigs. We confirmed the virulence of a virulent type strain and one representative clinical isolate, and the lack of virulence of two carriage isolates, in a pig infection model. Phylogenetic analysis of whole genome sequences of 124 isolates resulted in 10 groups, of which two were almost uniquely populated by clinical isolates. The population structure of S. suis serotype 9 appears highly diverse. However, analysis of the capsule loci sequences showed variation in a single region which fully correlated with a virulent genotype. Transmission electron microscopy suggested differences in capsule thickness between carriage and clinical genotypes. In conclusion, we found that that the S. suis serotype 9 population in the Netherlands is diverse. A distinct virulence-associated lineage was identified and could be discriminated based on the capsule locus sequence. Whilst the difference in virulence cannot be directly attributed to the DNA sequence, the correlation of capsule locus sequence with virulence could be used in the development of diagnostic tests to identify potential virulent S. suis serotype 9 in pigs.

Original languageEnglish
Article number15429
JournalScientific Reports
Volume9
Issue number1
DOIs
Publication statusPublished - 28 Oct 2019

Fingerprint

Streptococcus suis
Virulence
Swine
Capsules
Infection
Genotype
Serogroup
Transmission Electron Microscopy
Routine Diagnostic Tests
Netherlands
Population
Genome

Cite this

Willemse, Niels ; van der Ark, Kees C.H. ; Stockhofe-Zurwieden, Norbert ; Smith, Hilde ; Picavet, Daisy I. ; van Solt-Smits, Conny ; Wisselink, Henk J. ; Schultsz, Constance ; de Greeff, Astrid. / Clonal expansion of a virulent Streptococcus suis serotype 9 lineage distinguishable from carriage subpopulations. In: Scientific Reports. 2019 ; Vol. 9, No. 1.
@article{6ff3767844fe419a8e3e0723b0c6ceda,
title = "Clonal expansion of a virulent Streptococcus suis serotype 9 lineage distinguishable from carriage subpopulations",
abstract = "Streptococcus suis is a porcine pathogen, causing severe invasive infections. S. suis serotype 9 is increasingly causing disease in Dutch and Chinese pig herds, but it is unknown whether all serotype 9 isolates are equally virulent and markers that can identify virulent strains are not available. Therefore, discrimination between virulent isolates and carriage isolates typically not associated with disease, is currently not possible. We collected tonsillar S. suis isolates from 6 herds not previously diagnosed with S. suis infections, and clinical S. suis isolates of previously diseased pigs. We confirmed the virulence of a virulent type strain and one representative clinical isolate, and the lack of virulence of two carriage isolates, in a pig infection model. Phylogenetic analysis of whole genome sequences of 124 isolates resulted in 10 groups, of which two were almost uniquely populated by clinical isolates. The population structure of S. suis serotype 9 appears highly diverse. However, analysis of the capsule loci sequences showed variation in a single region which fully correlated with a virulent genotype. Transmission electron microscopy suggested differences in capsule thickness between carriage and clinical genotypes. In conclusion, we found that that the S. suis serotype 9 population in the Netherlands is diverse. A distinct virulence-associated lineage was identified and could be discriminated based on the capsule locus sequence. Whilst the difference in virulence cannot be directly attributed to the DNA sequence, the correlation of capsule locus sequence with virulence could be used in the development of diagnostic tests to identify potential virulent S. suis serotype 9 in pigs.",
author = "Niels Willemse and {van der Ark}, {Kees C.H.} and Norbert Stockhofe-Zurwieden and Hilde Smith and Picavet, {Daisy I.} and {van Solt-Smits}, Conny and Wisselink, {Henk J.} and Constance Schultsz and {de Greeff}, Astrid",
year = "2019",
month = "10",
day = "28",
doi = "10.1038/s41598-019-51576-0",
language = "English",
volume = "9",
journal = "Scientific Reports",
issn = "2045-2322",
publisher = "Nature Publishing Group",
number = "1",

}

Clonal expansion of a virulent Streptococcus suis serotype 9 lineage distinguishable from carriage subpopulations. / Willemse, Niels; van der Ark, Kees C.H.; Stockhofe-Zurwieden, Norbert; Smith, Hilde; Picavet, Daisy I.; van Solt-Smits, Conny; Wisselink, Henk J.; Schultsz, Constance; de Greeff, Astrid.

In: Scientific Reports, Vol. 9, No. 1, 15429, 28.10.2019.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Clonal expansion of a virulent Streptococcus suis serotype 9 lineage distinguishable from carriage subpopulations

AU - Willemse, Niels

AU - van der Ark, Kees C.H.

AU - Stockhofe-Zurwieden, Norbert

AU - Smith, Hilde

AU - Picavet, Daisy I.

AU - van Solt-Smits, Conny

AU - Wisselink, Henk J.

AU - Schultsz, Constance

AU - de Greeff, Astrid

PY - 2019/10/28

Y1 - 2019/10/28

N2 - Streptococcus suis is a porcine pathogen, causing severe invasive infections. S. suis serotype 9 is increasingly causing disease in Dutch and Chinese pig herds, but it is unknown whether all serotype 9 isolates are equally virulent and markers that can identify virulent strains are not available. Therefore, discrimination between virulent isolates and carriage isolates typically not associated with disease, is currently not possible. We collected tonsillar S. suis isolates from 6 herds not previously diagnosed with S. suis infections, and clinical S. suis isolates of previously diseased pigs. We confirmed the virulence of a virulent type strain and one representative clinical isolate, and the lack of virulence of two carriage isolates, in a pig infection model. Phylogenetic analysis of whole genome sequences of 124 isolates resulted in 10 groups, of which two were almost uniquely populated by clinical isolates. The population structure of S. suis serotype 9 appears highly diverse. However, analysis of the capsule loci sequences showed variation in a single region which fully correlated with a virulent genotype. Transmission electron microscopy suggested differences in capsule thickness between carriage and clinical genotypes. In conclusion, we found that that the S. suis serotype 9 population in the Netherlands is diverse. A distinct virulence-associated lineage was identified and could be discriminated based on the capsule locus sequence. Whilst the difference in virulence cannot be directly attributed to the DNA sequence, the correlation of capsule locus sequence with virulence could be used in the development of diagnostic tests to identify potential virulent S. suis serotype 9 in pigs.

AB - Streptococcus suis is a porcine pathogen, causing severe invasive infections. S. suis serotype 9 is increasingly causing disease in Dutch and Chinese pig herds, but it is unknown whether all serotype 9 isolates are equally virulent and markers that can identify virulent strains are not available. Therefore, discrimination between virulent isolates and carriage isolates typically not associated with disease, is currently not possible. We collected tonsillar S. suis isolates from 6 herds not previously diagnosed with S. suis infections, and clinical S. suis isolates of previously diseased pigs. We confirmed the virulence of a virulent type strain and one representative clinical isolate, and the lack of virulence of two carriage isolates, in a pig infection model. Phylogenetic analysis of whole genome sequences of 124 isolates resulted in 10 groups, of which two were almost uniquely populated by clinical isolates. The population structure of S. suis serotype 9 appears highly diverse. However, analysis of the capsule loci sequences showed variation in a single region which fully correlated with a virulent genotype. Transmission electron microscopy suggested differences in capsule thickness between carriage and clinical genotypes. In conclusion, we found that that the S. suis serotype 9 population in the Netherlands is diverse. A distinct virulence-associated lineage was identified and could be discriminated based on the capsule locus sequence. Whilst the difference in virulence cannot be directly attributed to the DNA sequence, the correlation of capsule locus sequence with virulence could be used in the development of diagnostic tests to identify potential virulent S. suis serotype 9 in pigs.

U2 - 10.1038/s41598-019-51576-0

DO - 10.1038/s41598-019-51576-0

M3 - Article

VL - 9

JO - Scientific Reports

JF - Scientific Reports

SN - 2045-2322

IS - 1

M1 - 15429

ER -