Quantitative and Qualitative Comparison of Virulence Traits, Including Murine Lethality, among Different M Types of Group A Streptococci

Abstract

Epidemiological studies have proposed an association between group A streptococci (GAS) bearing a particular M serological type and pathologic conditions such as streptococcal toxic shock syndrome (STSS). M1 and M3 GAS are isolated from STSS cases more frequently, whereas M4 and M12 GAS are isolated from non-STSS cases more frequently. To investigate whether there is any difference contributing the M-type association among GAS, we compared various virulence traits, including the murine lethality of M4, M12, M1, and M3 GAS clinical isolates, which are not clonally related to one another. Murine lethality, the activities of superantigens, streptolysin O, and nicotinamide adenine dinucleotide glycohydrolase, and the presence of the speA and speC genes were closely associated with M type. These results indicate that M types may serve, in part, as markers for strains/clones with particular profiles of virulence traits and mouse lethality.

Phages and the Evolution of Bacterial Pathogens: from Genomic Rearrangements to Lysogenic Conversion

“…These observations suggest that the S. pyogenes strains (M serotypes) have evolved as distinct pathovars, harboring a specific set of chromosomally encoded fitness factors. These data fit with the epidemiological observation of an association between the M serotype and certain pathological conditions in humans and mice (158). On the other hand, a detailed analysis of DNA sequence polymorphism of the set of chromosomal virulence genes studied by Reid et al (192) revealed numerous likely horizontal transfer events between the different M strains, and the authors suspected that generalized phage transduction was responsible for at least some of these gene transfers.…”

Cloning, Expression, and Characterization of the Superantigen Streptococcal Pyrogenic Exotoxin G from Streptococcus dysgalactiae

“…However, we found that GAS isolated from STSS cases produced smaller amounts of SAGs than did GAS isolated from non-STSS cases (21). Most SAGs have highly conserved secondary and tertiary structures despite minimal amino acid sequence homology.…”

“…Individual strains were stored in brain heart infusion (BHI) broth (Difco, Franklin Lakes, NJ) containing 7% dimethyl sulfoxide at Ϫ80°C until use. They were cultured overnight in BHI broth at 37°C in a humidified 5% CO 2 incubator as described previously (21). For expression of the six-His (His 6 )-tagged proteins, Escherichia coli M15(pREP4) (QIAGEN, Tokyo, Japan) was used for transformation with expression constructs derived from pQE30 (QIAGEN).…”

“…Briefly, bacteria grown in BHI broth overnight were collected and lysed by serial treatment with mutanolysin (Sigma-Aldrich, Tokyo, Japan), lysozyme, freeze-thaw cycling, and proteinase K (Sigma-Aldrich). S. dysgalactiae isolates were subjected to emm typing as described previously (http://www.cdc.gov/ncidod/biotech/strep /M-ProteinGene_typing.htm) (21). Briefly, genomic DNA from S. dysgalactiae was used as the template for PCR using specific primers A (5Ј-TATTAGCTTAG AAAATTAA-3Ј) and B (5Ј-GCAAGTTCTTCAGCTTGTTT-3Ј).…”

“…Large restriction fragment profiles of all of the isolates were obtained by SmaI digestion followed by pulsed-field gel electrophoresis (PFGE) as described previously (21). Briefly, plugs prepared from the isolates were treated sequentially with achromopeptidase, RNase, lysozyme, mutanolysin, sodium deoxycholate, sodium laurylsarcosine, Brij-58, EDTA, and proteinase K. After digestion with SmaI, the plugs were electrophoresed in a Genepath contourclamped homogeneous electric field apparatus (Bio-Rad Labs, Tokyo, Japan) and the patterns were analyzed with Molecular Analyst Fingerprinting Plus software, version 1.6 (Bio-Rad Laboratories, Inc., Hercules, CA).…”