Genotyping and investigating capsular polysaccharide synthesis gene loci of non-serotypeable Streptococcus suis isolated from diseased pigs in Canada

International audienceAbstractStreptococcus suis (S. suis) is an important swine pathogen and an emerging zoonotic agent. Most clinical S. suis strains express capsular polysaccharides (CPS), which can be typed by antisera using the coagglutination test. In this study, 79 S. suis strains recovered from diseased pigs in Canada and which could not be typed using antisera were further characterized by capsular gene typing and sequencing. Four patterns of cps locus were observed: (1) fifteen strains were grouped into previously reported serotypes but presented several mutations in their cps loci, when compared to available data from reference strains; (2) seven strains presented a complete deletion of the cps locus, which would result in an inability to synthesize capsule; (3) forty-seven strains were classified in recently described novel cps loci (NCLs); and (4) ten strains carried novel NCLs not previously described. Different virulence gene profiles (based on the presence of mrp, epf, and/or sly) were observed in these non-serotypeable strains. This study provides further insight in understanding the genetic characteristics of cps loci in non-serotypeable S. suis strains recovered from diseased animals. When using a combination of the previously described 35 serotypes and the complete NCL system, the number of untypeable strains recovered from diseased animals in Canada would be significantly reduced

Genomic comparisons of Streptococcus suis serotype 9 strains recovered from diseased pigs in Spain and Canada

Abstract Streptococcus suis is one of the most important bacterial pathogens in the porcine industry and also a zoonotic agent. Serotype 9 is becoming one of the most prevalent serotypes within the S. suis population in certain European countries. In the present study, serotype 9 strains isolated from a country where infection due to this serotype is endemic (Spain), were compared to those recovered from Canada, where this serotype is rarely isolated from diseased pigs. For comparison purposes, strains from Brazil and the only strain isolated from a human case, in Thailand, were also incorporated. Firstly, sequence types (STs) were obtained followed by detection of putative virulence factors. Phylogenetic trees were constructed using the non-recombinant single nucleotide polymorphisms from core genomes of tested strains. Most Spanish strains were either ST123 or ST125, whereas Canadian strains were highly heterogeneous. However, the distribution of putative virulence factors was similar in both groups of strains. The fact that ST16 strains harbored more putative virulence genes and shared greater similarity with the genome of human serotype 2 strains suggests that they present a higher zoonotic and virulence potential than those from Canada and Spain. More than 80% of the strains included in this study carried genes associated with resistance to tetracycline, lincosamides and macrolides. Serotype 9 strains may be nearly 400 years old and have evolved in parallel into 2 lineages. The rapid population expansion of dominant lineage 1 occurred within the last 40 years probably due to the rapid development of the porcine industry

MOESM1 of Genomic comparisons of Streptococcus suis serotype 9 strains recovered from diseased pigs in Spain and Canada

Additional file 1. Presence/absence of GZ1 genes in genomes of 34 S. suis serotype 9 strains and intermediately virulent serotype 2 strain 89-1591 identified in CGA. The presence or absence of a gene was coded as binary data with gene presence as 1 and gene absence as 0

MOESM1 of Genomic comparisons of Streptococcus suis serotype 9 strains recovered from diseased pigs in Spain and Canada

Additional file 1. Presence/absence of GZ1 genes in genomes of 34 S. suis serotype 9 strains and intermediately virulent serotype 2 strain 89-1591 identified in CGA. The presence or absence of a gene was coded as binary data with gene presence as 1 and gene absence as 0

MOESM2 of Genomic comparisons of Streptococcus suis serotype 9 strains recovered from diseased pigs in Spain and Canada

Additional file 2. Complete list of non-core virulence-associated genes present in S. suis serotype 9 strains tested. The presence or absence of a gene was coded as binary data with gene presence as “+” and absence as “−”. Complete genome of GZ0565 was used as reference for BFP66_RS01095, BFP66_RS1875, BFP66_RS7730, BFP66_RS8445, BFP66_RS9410 and Ag like protein (BFP66_04530). Complete genome of GZ1 was used as reference for other virulence genes