title: Genetic diversity of Streptococcus suis isolates as determined by comparative genome hybridization.
abstract: BACKGROUND
  Streptococcus suis is a zoonotic pathogen that causes infections in young piglets. S. suis is a heterogeneous species. Thirty-three different capsular serotypes have been described, that differ in virulence between as well as within serotypes.
  
  
  RESULTS
  In this study, the correlation between gene content, serotype, phenotype and virulence among 55 S. suis strains was studied using Comparative Genome Hybridization (CGH). Clustering of CGH data divided S. suis isolates into two clusters, A and B. Cluster A isolates could be discriminated from cluster B isolates based on the protein expression of extracellular factor (EF). Cluster A contained serotype 1 and 2 isolates that were correlated with virulence. Cluster B mainly contained serotype 7 and 9 isolates. Genetic similarity was observed between serotype 7 and serotype 2 isolates that do not express muramidase released protein (MRP) and EF (MRP⁻EF⁻), suggesting these isolates originated from a common founder. Profiles of 25 putative virulence-associated genes of S. suis were determined among the 55 isolates. Presence of all 25 genes was shown for cluster A isolates, whereas cluster B isolates lacked one or more putative virulence genes. Divergence of S. suis isolates was further studied based on the presence of 39 regions of difference. Conservation of genes was evaluated by the definition of a core genome that contained 78% of all ORFs in P1/7.
  
  
  CONCLUSIONS
  In conclusion, we show that CGH is a valuable method to study distribution of genes or gene clusters among isolates in detail, yielding information on genetic similarity, and virulence traits of S. suis isolates.
authors: Infection Biology, Central Veterinary Institute of Wageningen UR (University & Research Centre), Edelhertweg 15, Lelystad, 8219 PH, The Netherlands. astrid.degreeff@wur.nl
authors: Astrid
authors: A
authors: de Greeff
authors: Henk J
authors: HJ
authors: Wisselink
authors: Freddy M
authors: FM
authors: de Bree
authors: Constance
authors: C
authors: Schultsz
authors: Christoph G
authors: CG
authors: Baums
authors: Hoa Ngo
authors: HN
authors: Thi
authors: Norbert
authors: N
authors: Stockhofe-Zurwieden
authors: Hilde E
authors: HE
authors: Smith
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D015373:Bacterial Typing Techniques; D016000:Cluster Analysis; D055028:Comparative Genomic Hybridization; D014644:Genetic Variation; D005838:Genotype; D010641:Phenotype; D012703:Serotyping; D013290:Streptococcal Infections / Q000382:microbiology / Q000662:veterinary*; D017011:Streptococcus suis / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification* / Q000472:pathogenicity; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology*; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D037521:Virulence Factors