title: Characterization of Streptococcus suis serotype 2 isolates from China.
abstract: Streptococcus suis (S. suis) is a major pathogen in the pig industry and an important zoonotic agent that causes severe invasive diseases in humans. Previous studies based on multilocus sequence typing (MLST) and the associations between sequence types and genotypes or virulence suggested that North American S. suis serotype 2 isolates are composed of multiple populations. This study investigated the population structure of S. suis serotype 2 isolates in China. We constructed a phylogenetic tree for S. suis serotype 2 isolates based on 16S rRNA gene typing and MLST, studied associations between clades and sources, analyzed the genotype distributions of virulence markers [muramidase-released protein (MRP), extracellular protein factor (EF), and suilysin (SLY)] in different clades, computed the selection pressures for these virulence marker genes, and verified the associations between clades and virulence. There were two primary clades (populations) in the phylogenetic tree of S. suis serotype 2. The two populations were associated with different tissue tropisms. The genotypic distributions and selection pressures of MRP, EF, and SLY were different between the two populations, which suggested that they had different evolutionary paths. The two populations also displayed differences in virulence in experimentally infected mice. The results provide insights into the population structure of S. suis serotype 2 isolates in China and suggest that S. suis serotype 2 clade 1 is an overlooked population that deserves further evaluation.
authors.affiliation: College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, PR China.
authors.forename: Weifeng
authors.initials: W
authors.lastname: Zhu
authors.forename: Chao
authors.initials: C
authors.lastname: Wu
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Sun
authors.forename: Anding
authors.initials: A
authors.lastname: Zhang
authors.forename: Jian
authors.initials: J
authors.lastname: Zhu
authors.forename: Yafeng
authors.initials: Y
authors.lastname: Hua
authors.forename: Huanchun
authors.initials: H
authors.lastname: Chen
authors.forename: Meilin
authors.initials: M
authors.lastname: Jin
mesh_terms: D000818:Animals; D002681:China; D005838:Genotype; D051379:Mice; D008969:Molecular Sequence Data; D058885:Multilocus Sequence Typing; D010802:Phylogeny; D012703:Serotyping / Q000662:veterinary; 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*; D037521:Virulence Factors / Q000235:genetics
chemical_list: D037521:Virulence Factors
keywords: Genotype; Population structure; Streptococcus suis; Tissue tropism