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Distribution of capsular serotypes and virulence markers of Streptococcus suis isolated from pigs with polyserositis in Korea.

ABSTRACT: The objective of this study was to determine the capsular serotypes and potential virulence factors of Streptococcus suis isolated from pigs with polyserositis. Among the 24 isolates evaluated, serotype 3 [7 (29%) of the isolates] and serotype 4 [5 (21%)] were the most common. The isolates were also studied for the presence of the genes mrp, epf, and sly, which encode muramidase-released protein (MRP), extracellular factor (EF), and suilysin (SLY), respectively. Of the 24 isolates, 8 carried mrp: 4 of serotype 3, 2 of serotype 2, and 2 of serotype 4. One mrp(+) isolate (serotype 2) also carried the epf gene. All 24 isolates carried the sly gene. The serotype and genotype distribution greatly differed from that reported for isolates from pigs with other clinical manifestations of S. suis infection in other countries.

SUBMITTER: Kim D

PROVIDER: S-EPMC2949345 | biostudies-literature | 2010 Oct

REPOSITORIES: biostudies-literature

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Distribution of capsular serotypes and virulence markers of Streptococcus suis isolated from pigs with polyserositis in Korea.

Kim Duyeol D Han Kiwon K Oh Yeonsu Y Kim Chung Hyun CH Kang Ikjae I Lee Jeehoon J Gottschalk Marcelo M Chae Chanhee C

Canadian journal of veterinary research = Revue canadienne de recherche veterinaire 20101001 4

The objective of this study was to determine the capsular serotypes and potential virulence factors of Streptococcus suis isolated from pigs with polyserositis. Among the 24 isolates evaluated, serotype 3 [7 (29%) of the isolates] and serotype 4 [5 (21%)] were the most common. The isolates were also studied for the presence of the genes mrp, epf, and sly, which encode muramidase-released protein (MRP), extracellular factor (EF), and suilysin (SLY), respectively. Of the 24 isolates, 8 carried mrp ...[more]

PMID: 21197232

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Project description:Streptococcus suis is an important porcine bacterial pathogen and a zoonotic agent responsible for sudden death, septic shock and meningitis, of which serotype 2 is the most widespread, with serotype 14 also causing infections in humans in South-East Asia. Knowledge of its pathogenesis and virulence are almost exclusively based on these two serotypes. Though serotype 9 is responsible for the greatest number of porcine cases in Spain, the Netherlands and Germany, very little information is currently available regarding this serotype. Of the different virulence factors, the capsular polysaccharide (CPS) is required for S. suis virulence as it promotes resistance to phagocytosis and killing and masks surface components responsible for host cell activation. However, these roles have been described for serotypes 2 and 14, whose CPSs are structurally and compositionally similar, both containing sialic acid. Consequently, we evaluated herein the interactions of serotype 9 with host cells and the role of its CPS, which greatly differs from those of serotypes 2 and 14. Results demonstrated that serotype 9 adhesion to but not invasion of respiratory epithelial cells was greater than that of serotypes 2 and 14. Furthermore serotype 9 was more internalized by macrophages but equally resistant to whole blood killing. Though recognition of serotypes 2, 9 and 14 by DCs required MyD88-dependent signaling, in vitro pro-inflammatory mediator production induced by serotype 9 was much lower. In vivo, however, serotype 9 causes an exacerbated inflammatory response, which combined with persistent bacterial presence, is probably responsible for host death during the systemic infection. Though presence of the serotype 9 CPS masks surface components less efficiently than those of serotypes 2 and 14, the serotype 9 CPS remains critical for virulence as it is required for survival in blood and development of clinical disease, and this regardless of its unique composition and structure.

Project description:The capsular polysaccharide (CPS) represents a key virulence factor for most encapsulated streptococci. Streptococcus suis and Group B Streptococcus (GBS) are both well-encapsulated pathogens of clinical importance in veterinary and/or human medicine and responsible for invasive systemic diseases. S. suis and GBS are the only Gram-positive bacteria which express a sialylated CPS at their surface. An important difference between these two sialylated CPSs is the linkage between the side-chain terminal galactose and sialic acid, being ?-2,6 for S. suis but ?-2,3 for GBS. It is still unclear how sialic acid may affect CPS production and, consequently, the pathogenesis of the disease caused by these two bacterial pathogens. Here, we investigated the role of sialic acid and the putative effect of sialic acid linkage modification in CPS synthesis using inter-species allelic exchange mutagenesis. To this aim, a new molecular biogenetic approach to express CPS with modified sialic acid linkage was developed. We showed that sialic acid (and its ?-2,6 linkage) is crucial for S. suis CPS synthesis, whereas for GBS, CPS synthesis may occur in presence of an ?-2,6 sialyltransferase or in absence of sialic acid moiety. To evaluate the effect of the CPS composition/structure on sialyltransferase activity, two distinct capsular serotypes within each bacterial species were compared (S. suis serotypes 2 and 14 and GBS serotypes III and V). It was demonstrated that the observed differences in sialyltransferase activity and specificity between S. suis and GBS were serotype unrestricted. This is the first time that a study investigates the interspecies exchange of capsular sialyltransferase genes in Gram-positive bacteria. The obtained mutants represent novel tools that could be used to further investigate the immunomodulatory properties of sialylated CPSs. Finally, in spite of common CPS structural characteristics and similarities in the cps loci, sialic acid exerts differential control of CPS expression by S. suis and GBS.

Dataset Information

Distribution of capsular serotypes and virulence markers of Streptococcus suis isolated from pigs with polyserositis in Korea.

Publications

Distribution of capsular serotypes and virulence markers of Streptococcus suis isolated from pigs with polyserositis in Korea.

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