The relationship between opacity factor and M protein in Streptococcus pyogenes

Hallas, Gillian; Widdowson, Jean P.

doi:10.1099/00222615-16-1-13

Cited by 10 publications

(9 citation statements)

References 15 publications

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“…The possibility that some of these strains were M negative variants was suggested by the fact that strain 8330 (T type 22) was opacity factor negative (all M-positive strains with the T22 antigen are opacity factor positive). Cultures lacking an M antigen will not survive in fresh human blood and have a lower content of M-associated protein (MAP; Hallas & Widdowson, 1983) SPE A and B toxins by ammonium sulphate precipitation as described by Harboe & Ingild (1973). Isolation of toxins from reference strains.SPE A.…”

Section: Methodsmentioning

confidence: 99%

The production of pyrogenic exotoxins by group A streptococci

Hallas¹

1985

J. Hyg.

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SUMMARYLancefield group A streptococci isolated from recent outbreaks and sporadic cases of scarlet fever were restricted to the following M types 1, 3, 4, 6, 12, 18, 22 and 66. These strains were examined for the presence of streptococcal pyrogenic exotoxins (SPE) types A, B and C by isoelectric focusing in polyacrylamide gels and by immunoprecipitation in agar gels. SPE B was produced by 70 % of the strains and SPE C by 4000. SPE A could not be detected in these strains. In contrast, SPE type A was found in 4 of 10 strains, held by the NCTC, that had been isolated before 1940 from patients with scarlet fever. Nine of 12 recent isolates from patients with sore throat uncomplicated by a rash produced SPE C and 4 of these also produced SPE B.

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Section: Methodsmentioning

confidence: 99%

The production of pyrogenic exotoxins by group A streptococci

Hallas¹

1985

J. Hyg.

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“…SOF is an extracellular lipoproteinase that makes human serum opaque, binds to fibronectin and fibrinogen, and is a virulence factor in mice infected with serotype M2 GAS [47][48][49]. GAS strains historically have been divided into 2 groups (SOF-pos- Figure 2.…”

Section: Serum Opacity Factor (Sof) Gene Regionmentioning

confidence: 99%

Genome Sequence of a Serotype M28 Strain of Group AStreptococcus:Potential New Insights into Puerperal Sepsis and Bacterial Disease Specificity

Green¹,

Zhang²,

Porcella³

et al. 2005

J INFECT DIS

218

214

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Puerperal sepsis, a major cause of death of young women in Europe in the 1800s, was due predominantly to the gram-positive pathogen group A Streptococcus. Studies conducted during past decades have shown that serotype M28 strains are the major group A Streptococcus organisms responsible for many of these infections. To begin to increase our understanding of their enrichment in puerperal sepsis, we sequenced the genome of a genetically representative strain. This strain has genes encoding a novel array of prophage virulence factors, cell-surface proteins, and other molecules likely to contribute to host-pathogen interactions. Importantly, genes for 7 inferred extracellular proteins are encoded by a 37.4-kb foreign DNA element that is shared with group B Streptococcus and is present in all serotype M28 strains. Proteins encoded by the 37.4-kb element were expressed extracellularly and in human infections. Acquisition of foreign genes has helped create a disease-specialist clone of this pathogen.

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“…For example, a strain with a type 49 M protein will always express a type 49 OF. The two antigens, however, are separable both by purification (18) and by genetic means (8). Clearly, the processes responsible for M protein antigenic diversity must in some way be coordinated with the mechanisms of diversity of these other variant surface antigens.…”

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confidence: 99%

Identification of a divergent M protein gene and an M protein-related gene family in Streptococcus pyogenes serotype 49

1989

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The antigenically variant M protein of Streptococcus pyogenes enhances virulence by promoting resistance to phagocytosis. The serum opacity factor (OF), produced by a subset of M serotypes, is also antigenically variant, and its antigenic variability exactly parallels that of M protein. OF-positive and OF-negative streptococci are also phenotypically distinguishable by a number of other criteria. In order to study the differences between OF-positive and OF-negative streptococci, we cloned and sequenced the type 49 M protein gene (emm49), the first to be cloned from an OF-positive strain. This gene showed evolutionary divergence from the OF-negative M protein genes studied previously. Furthermore, emm49 was part of a gene family, in contrast to the single-copy nature of previously characterized M protein genes.The M protein, a major virulence factor of Streptococcus pyogenes (group A streptococci), enhances the pathogenicity of the organism by blocking phagocytosis in the nonimmunized host (26,27). Antibodies to M protein develop in infected individuals and confer immunity (34). Streptococcal M protein, however, is antigenically variant, and opsonic antibodies to M protein are largely type specific. Thus, with 70 or more M protein serotypes (35), group A streptococci can successfully avoid immune surveillance.Molecular biological techniques have increased our knowledge of the structure of M protein and its antigenic variability. Five M protein genes have been cloned, and all have been at least partially sequenced (16,24,40,42,46). The M proteins encoded by these sequenced genes have a common framework which includes a conserved signal peptide, a hypervariable amino terminus, and a highly conserved C-terminus. Each gene also appears to contain some internal sequence repetitions, although the extent and degree of similarity of these repeats vary among the genes. Furthermore, regions preceding and following these M protein genes are conserved (16,42). This suggests that the genes are situated in a common expression site on the streptococcal chromosome.Our understanding of how the M protein hypervariable regions evolved is still incomplete. Duplication and deletion of intragenic repeats present in the variable regions of M molecules is a possible mechanism for the introduction of variant amino acids into the M protein sequences (25). Recent evidence shows that intragenic recombination can indeed introduce variant opsonic determinants into the repetitive regions of the M6 protein (28). Not all of the opsonic antigenic determinants of M proteins, however, are located in the repetitive regions of the molecules (25, 32). Thus, additional mechanisms must be involved in the generation of M protein antigenic diversity.A model explaining the generation of M protein antigenic diversity must account for the fact that other streptococcal proteins exhibit antigenic diversity in a nonrandom manner relative to the M type. Among these are the T antigen, a * Corresponding author. (18) and by genetic means (8). Clearly, the processe...

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The relationship between opacity factor and M protein in Streptococcus pyogenes

Cited by 10 publications

References 15 publications

The production of pyrogenic exotoxins by group A streptococci

The production of pyrogenic exotoxins by group A streptococci

Genome Sequence of a Serotype M28 Strain of Group AStreptococcus:Potential New Insights into Puerperal Sepsis and Bacterial Disease Specificity

Identification of a divergent M protein gene and an M protein-related gene family in Streptococcus pyogenes serotype 49

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