The cps Genes of Streptococcus suis Serotypes 1, 2, and 9: Development of Rapid Serotype-Specific PCR Assays

Abstract

We developed three type-specific PCR assays for the rapid and sensitive detection of Streptococcus suis serotype 1 (plus 14), serotype 2 (plus 1/2), and serotype 9 strains in tonsillar specimens from pigs. The PCR primers were based on the sequences of type-specific capsular genes of S. suis serotype 1, 2, and 9 strains. We recently characterized a major part of the capsular biosynthesis (cps) locus of S. suis serotype 2. Here we extended these studies and characterized major parts of thecps loci of S. suis serotypes 1 and 9. Type-specific genes were identified by cross-hybridization experiments between the individual cps genes and chromosomal DNAs from the 35 different serotypes. Four genes of S. suis serotype 1 specifically hybridized with serotype 1 and 14 strains only. Five genes of S. suis serotype 2 specifically hybridized with serotype 2 and 1/2 strains only, and two genes of S. suisserotype 9 specifically hybridized with serotype 9 strains. Until now rapid and sensitive diagnostic tests were available only for pathogenic strains of serotype 2 and highly pathogenic strains of serotype 1. The serotype-specific PCR assays can therefore be useful tools for the identification of serotype 1, 14, 2, 1/2, and 9 strains both for diagnostic purposes and in epidemiological and transmission studies. Therefore, these tests may facilitate control and eradication programs.

Rapid PCR test for Streptococcus suis serotype 7

“…The results are summarized in Table 2. As expected, based on the data obtained with the cps9E probe [15], the cps7E probe hybridized with chromosomal DNA of many di¡erent S. suis serotypes. The cps7F and cps7G probes showed hybridization with chromosomal DNA of S. suis serotypes 4, 5, 7, 17 This work (Fig.…”

“…Until now, such a diagnostic test was not available for serotype 7 strains. We recently showed that the serotype 1, 2 and 9-speci¢c PCR assays could easily be performed on clinical samples [15]. Although it has not been tested yet, similar results are expected for the serotype 7-speci¢c PCR test.…”

“…To isolate the type-speci¢c cps genes of S. suis serotype 7, the cps9E gene of serotype 9 was used as a probe to identify chromosomal DNA fragments of type 7 containing homologous DNA sequences [15]. A 1.6-kb PstI fragment was identi¢ed and cloned in pKUN19.…”

“…Recently, rapid and sensitive PCR assays speci¢c for serotypes 2 (and 1/2), 1 (and 14) and 9 were developed [15]. These assays were based on the capsular polysaccharide biosynthesis loci (cps) of S. suis serotypes 2, 1 and 9 [15,16]. Until now, no rapid and sensitive diagnostic test is available for S. suis serotype 7.…”

Changes in abundance of Lactobacillus spp. and Streptococcus suis in the stomach, jejunum and ileum of piglets after weaning

“…Streptococcus suis is an important cause of meningitis, septicaemia, arthritis and sudden death in young pigs (Clifton-Hadley, 1983;Vecht et al, 1992) and can infect humans (Arends & Zanen, 1988;Trottier et al, 1991), as evidenced in the outbreaks in China in 1998 and 2005 (Lu, 2005). Currently, bacteriological techniques and PCR tests are routinely applied to detect or characterize S. suis in pure cultures (Smith et al, 1999;Wisselink et al, 2002). Here, we developed a fast and sensitive, cultivation-independent, real-time PCR assay to quantify S. suis in samples from the porcine intestine, which is inhabited by a complex microbial community.…”