Detection of genomic heterogeneity in Streptococcus suis isolates by DNA restriction fragment length polymorphisms of rRNA genes (ribotyping)

Abstract

Whole-cell chromosomal digests of 54 isolates of Streptococcus suis encompassing all known serotypes from a geographically varied collection were examined by PstI restriction fragment length polymorphisms and then hybridized with a digoxigenin-11-dUTP-labeled cDNA probe transcribed from a mixture of 16S and 23S rRNAs from Escherichia coli MRE600. The hybridization patterns showed genetic heterogeneity within and between S. suis serotypes. Most isolates (87%) representing 28 serotypes contained a common band at ϳ1.8 kb. However, 13% of the isolates representing seven serotypes lacked the 1.8-kb band, indicating that the species as currently defined is diverse. Nonetheless, the 1.8-kb band may be a useful genotypic marker for identification of most S. suis isolates. We tested the ability of this technique to discriminate between virulent and avirulent S. suis type 2 isolates. A virulent strain of S. suis type 2 could be distinguished from avirulent strains by the presence of specific bands. No correlation was obvious between band pattern and hemolysin production.

Hybridization analysis of the gene encoding a hemolysin (suilysin) of Streptococcus suis type 2: evidence for the absence of the gene in some isolates

“…The 63 S. suis strains used in this study were obtained from varied geographical location and their sources, cultivation and DNA extraction methods have been described previously [11,18]. Additionally, all S. suis type 2 tested were grown on sheep blood agar plates (Remel, Lenexa, KS, USA) for hemolytic phenotype.…”

“…6, isolates 86-3977B, 1933, D930) hybridized to the suilysin gene probes to give the 4.0 kb band. The pathogenicity of isolate DH5 has been controversial [11,18]. All of the avirulent and moderately virulent isolates possessed the 1.2 kb band, suggesting that the hybridization pattern with the suilysin gene probe might be useful for identi¢cation of most highly virulent isolates.…”

Phylogenetic analysis ofBacillus thuringiensisserovars based on 16S rRNA gene restriction fragment length polymorphisms

“…For speci®c purposes, other methods, such as plasmid pattern analysis (Lereclus et al 1982), immunological tests using monoclonal antibody against crystal proteins (Lynch and Baumann 1985) and identi®cation of the crystal protein gene using speci®c DNA probes (Visser 1989), were introduced. Some molecular typing methods, such as Arbitrary Primer-PCR technology (Brousseau et al 1993), DNA reassociation measurements (Nakamura 1994), ribosomal RNA gene restriction fragment length polymorphism (Priest et al 1994;Akhurst et al 1997), ribosomal RNA gene intergenic spacer sequences comparison (Bourque et al 1995), and DNA-colony hybridization and random ampli®ed polymorphic DNA (RAPD) analysis (Hansen et al 1998), have also been applied to limited numbers of B. thuringiensis strains.…”

“…One of the genotype-based molecular typing methods, 16S rRNA gene restriction fragment length polymorphism (ribotyping), has proved to be very effective as a molecular taxonomic tool for estimating chromosomal genetic diversity and relationships among various bacterial species and subspecies (Saunders et al 1988;Grimont and Grimont 1991;Hernandez et al 1991;Williams and Collins 1991;Jacquet et al 1992;Mugnai et al 1994;Okwumabua et al 1995). As this technique is based on a DNA±DNA hybridization experiment, it can give more stable, reliable and robust results than approaches based on phenotypic data.…”

A polymerase chain reaction (PCR) assay specific for Streptococcus suis based on the gene encoding the glutamate dehydrogenase

“…The development of a sensitive DNA-based assay for the identi-¢cation of S. suis isolated from clinical specimens may improve the rapidity and accuracy of the diagnosis. One of the di⁄culties associated with the development of a diagnostic assay, and a heterologous vaccine for S. suis is that strains of this organism exhibit extensive genetic heterogeneity within and between serotypes [2,6]. Thus, identi¢cation of an antigenic factor or DNA region conserved across capsular types or pathogenic strains irrespective of geographic origin may help to obviate this problem.…”