Genetic and virulence characterization of Streptococcus suis type 2 isolates from swine in the provinces of Zhejiang and Henan, China

Abstract

This study was aimed to examine the genetic characteristics of 44 Streptococcus suis type 2 (SS2) isolates and the virulence attributes of 23 representative isolates. Multilocus sequence typing revealed five sequence types (ST1, ST7, ST28, ST86, and ST162) with 19 isolates assigned to ST7 (43.2%), 14 to ST1 (31.8%), and 9 to ST28 (20.5%). PCR typing of the pilus gene clusters classified the isolates into three types: A (72.7%), B (22.7%), and N (4.5%). All isolates of pilus types A and N were assigned to the ST1 complex containing ST1, ST7, and ST86, while those of type B belonged to the ST27 complex comprising ST28 and ST162. Only two strains had the putative pathogenicity island 89-kb cluster (89K) and were of type N. The type B strains had a significantly lower adhesion, were more readily killed by macrophage, and had lower virulence to mice than those of types A and N. We conclude that SS2 strains of both ST1 and ST27 complexes, parallel to pilus types A and B, were prevalent in the pig populations in Zhejiang Province, and ST7 and ST1 strains were the predominant genotypes in the diseased pigs with pneumonia.

Prevalence of <i>Streptococcus suis</i> Genotypes in Isolates from Porcine Endocarditis in East Japan

“…The remaining four isolates showed three different genotypes (nt/mrp+/epf−/sly+/sbp2−/sep1−/sgp1−, nt/mrp*/ epf−/sly+/sbp2+/sep1+/sgp1− and nt/mrp−/epf−/sly−/ sbp2−/sep1−/sgp1−) ( Table 1). Although there were some exceptions [17,20], most of the sbp2+/sep1+/sgp1− and sbp2−/sep1−/sgp1− isolates belonged to neither ST1 complex nor ST27 (currently ST28) complex [17]. In this study, the representative isolates were also classified into neither of the two important clonal groups (Table 1).…”

“…suis is classified into more than 30 serotypes according to the different antigenicity of its capsular polysaccharides, and serotype 2 has been most frequently isolated from both infected pigs and humans in many countries [4,23]. Among the serotype 2 strains, muraminidase-released protein (MRP) and extracellular factor (EF), encoded by mrp and epf, respectively, are frequently associated with virulent strains [21], and thus mrp and epf are often used as virulence-associated markers for epidemiological studies of S. suis [3,6,7,12,13,15,18,20,24]. In addition to these two genes, sly encoding a cytotoxin (Suilysin) is also frequently used as a virulence-associated marker [3,6,7,12,13,15,18,20,24].…”

“…Among the serotype 2 strains, muraminidase-released protein (MRP) and extracellular factor (EF), encoded by mrp and epf, respectively, are frequently associated with virulent strains [21], and thus mrp and epf are often used as virulence-associated markers for epidemiological studies of S. suis [3,6,7,12,13,15,18,20,24]. In addition to these two genes, sly encoding a cytotoxin (Suilysin) is also frequently used as a virulence-associated marker [3,6,7,12,13,15,18,20,24]. Several previous studies that investigated the profiles of these genes suggested some correlation between the virulence-associated gene profiles and STs of S. suis strains/isolates [3,6,12,13,18].…”

Streptococcus suis, an important pig pathogen and emerging zoonotic agent—an update on the worldwide distribution based on serotyping and sequence typing

“…52,242,244,245,246,248 Nevertheless, other important genetic differences vary between ST1 and ST7 strains including the presence of a 89K pathogenicity island in ST7 strains. 251 These ST1 complex strains interestingly differ from not only the human serotype 2 ST104 strains of Thailand which are sly + mrp - epf - but also from the human serotype 2 ST20 strains recovered in the Netherlands that were epf -.…”

Antimicrobial Susceptibility, Tetracycline and Erythromycin Resistance Genes, and Multilocus Sequence Typing of <i>Streptococcus suis</i> Isolates from Diseased Pigs in China

“…However, mechanisms, which contribute to the tetracycline and macrolide resistance in Chinese S. suis strains, are still poorly understood. Besides, although several approaches have been used to characterize S. suis isolates from diseased pigs in limited geographic regions in China [13,22], knowledge about the current epidemiological status of S. suis in Chin is still limited. Therefore, in this study, we investigated the antimicrobial resistance patterns, tetracycline and erythromycin resistance genes, Serotypes and STs of S. suis isolated from diseased pigs in central and eastern regions of China.…”