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Virulence Genes and Genetic Diversity of Streptococcus suis Serotype 2 Isolates from Thailand
Author(s) -
Maneerat K.,
Yongkiettrakul S.,
Kramomtong I.,
Tongtawe P.,
Tapchaisri P.,
Luangsuk P.,
Chaicumpa W.,
Gottschalk M.,
Srimanote P.
Publication year - 2013
Publication title -
transboundary and emerging diseases
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.392
H-Index - 63
eISSN - 1865-1682
pISSN - 1865-1674
DOI - 10.1111/tbed.12157
Subject(s) - streptococcus suis , multilocus sequence typing , biology , virulence , serotype , microbiology and biotechnology , rapd , typing , gene , genotype , genetics , genetic diversity , virology , population , sociology , demography
Summary Isolates of S treptococcus suis from different W estern countries as well as those from C hina and V ietnam have been previously well characterized. So far, the genetic characteristics and relationship between S. suis strains isolated from both humans and pigs in T hailand are unknown. In this study, a total of 245 S. suis isolates were collected from both human cases (epidemic and sporadic) and pigs (diseased and asymptomatic) in T hailand. Bacterial strains were identified by biochemical tests and PCR targeting both, the 16S rRNA and gdh genes. Thirty‐six isolates were identified as serotype 2 based on serotyping and the cps2 ‐ PCR . These isolates were tested for the presence of six virulence‐associated genes: an arginine deiminase ( arcA ), a 38‐kDa protein and protective antigen ( bay046 ), an extracellular factor ( epf ), an hyaluronidase ( hyl ), a muramidase‐released protein ( mrp ) and a suilysin ( sly ). In addition, the genetic diversities of these isolates were studied by RAPD PCR and multilocus sequence typing (MLST) analysis. Four virulence‐associated gene patterns (VAGP 1 to 4) were obtained, and the majority of isolates (32/36) carried all genes tested (VAGP1). Each of the three OPB primers used provided 4 patterns designated RAPD‐A to RAPD‐D. Furthermore, MLST analysis could also distinguish the 36 isolates into four sequence types (STs): ST1 ( n = 32), ST104 ( n = 2), ST233 ( n = 1) and a newly identified ST , ST336 ( n = 1). Dendrogram constructions based on RAPD patterns indicated that S. suis serotype 2 isolates from T hailand could be divided into four groups and that the characteristics of the individual groups were in complete agreement with the virulence gene profiles and ST s. The majority (32/36) of isolates recovered from diseased pigs, slaughterhouse pigs or human patients could be classified into a single group (VAGP1, RAPD‐A and ST1). This genetic information strongly suggests the transmission of S. suis isolates from pigs to humans in T hailand. Our findings are the first to report genetic characteristics of strains from T hailand and to elucidate the genetic relationship among S. suis isolates from human and pig origins.