Molecular aspects of the phagocytosis resistance of group a streptococci

Manjula, Belur N.

doi:10.1007/bf00148912

Cited by 12 publications

(4 citation statements)

References 90 publications

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“…Some earlier studies did examine the association of streptococci with neutrophils by light microscopy (Beachey and Cunningham, 1973;Whitnack et al ., 1984;Dale et al, 1996;Dale et al, 1999), but as it is very difficult to differentiate between internalized and attached bacteria by this method, the association of bacteria with cells rather than phagocytosis was determined in most of these studies. Nevertheless, it became generally accepted that M protein is a major antiphagocytic determinant of group A streptococcus (reviewed by Manjula, 1988). The interaction of human neutrophils with S. pyogenes labelled with the fluorophore BCECF has also been studied using flow cytometry and microscopy (Schnitzler et al, 1995;Podbielski et al, 1996).…”

Section: Discussionmentioning

confidence: 99%

Streptococcus pyogenes expressing M and M-like surface proteins are phagocytosed but survive inside human neutrophils

Staali¹,

Mörgelin²,

Björck³

et al. 2003

Cell Microbiol

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SummaryStrains of the Gram-positive human pathogen Streptococcus pyogenes (group A streptococcus ) that express surface-associated M or M-like proteins survive and grow in non-immune fresh human blood. This is generally accepted to be caused by an antiphagocytic property of these proteins. However, in most previous studies, an inhibition of the internalization of the bacteria into host cells has not been studied or not directly demonstrated. Therefore, in the present paper, we used flow cytometry, fluorescence microscopy and electron microscopy to study phagocytosis by human neutrophils of wild-type S. pyogenes and strains deficient in expression of M protein and/or the M-like protein H. The results demonstrate that all strains of S. pyogenes tested, including the wild-type AP1 strain, induce actin polymerization and are efficiently phagocytosed by human neutrophils. In addition, using classical bactericidal assays, we show that the wild-type AP1 strain can survive inside neutrophils, whereas mutant strains are rapidly killed. We conclude that the ability of virulent S. pyogenes to survive and multiply in whole blood is most likely not possible to explain only by an antiphagocytic effect of bacterial surface components. Instead, our data suggest that bacterial evasion of host defences occurs intracellularly and that survival inside human neutrophils may contribute to the pathogenesis of S. pyogenes and the recurrence of S. pyogenes infections.

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Section: Discussionmentioning

confidence: 99%

Streptococcus pyogenes expressing M and M-like surface proteins are phagocytosed but survive inside human neutrophils

Staali¹,

Mörgelin²,

Björck³

et al. 2003

Cell Microbiol

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“…M proteins of Streptococcus pyogenes are important pathogenicity factors of pyogenic streptococci (4,18,32). They are receptor proteins which can show multiple binding to different plasma proteins, like fibrinogen, albumin, and immunoglobulin G (11,16,30,31); complement factor H (9); and fibronectin (30).…”

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“…More recently, it was reported that other M protein serotypes also have superantigenic properties. M proteins purified by limited pepsin digestion of type 2, 5,6,18,19, and 24 streptococci were also stimulators of human T cells and stimulated T cells with different individual V␤s (38). The investigators concluded that in their N termini, variable M proteins represent a family of streptococcal superantigens analogous to the structurally related family of staphylococcal enterotoxin superantigens.…”

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confidence: 99%

Mitogenicity of M5 protein extracted from Streptococcus pyogenes cells is due to streptococcal pyrogenic exotoxin C and mitogenic factor MF

et al. 1995

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M proteins of Streptococcus pyogenes are virulence factors which impede phagocytosis, bind to many plasma proteins, and induce formation of cross-reactive autoimmune antibodies. Recently, it has been reported that some M proteins, extracted with pepsin from streptococci (pep M), are superantigens. One of these, pep M5, was investigated in detail and was shown to stimulate human T cells bearing V␤2, V␤4, and V␤8. In the present study, we extracted and purified M5 protein by different biochemical methods from two M type 5 group A streptococcal strains. The crude extracts were fractionated by affinity chromatography and ion-exchange chromatography. All fractions were tested in parallel for M protein by immunoblotting and for T-cellstimulating activity. Although several crude preparations of M5 protein were associated with mitogenicity for V␤2 and V␤8 T cells, the M5 proteins, irrespective of the extraction method, could be purified to the extent that they were no longer mitogenic. The mitogenic activity was not destroyed during the purification procedures but was found in fractions separated from M protein. In these fractions, streptococcal pyrogenic exotoxin C and mitogenic factor MF could be detected by protein blotting and enzyme-linked immunosorbent assay. Moreover, anti-M protein sera did not inhibit the mitogenic activity of crude extracts, but antisera which contained anti-streptococcal pyrogenic exotoxin C antibodies showed inhibition. The inability of M5 protein to stimulate T cells was confirmed with recombinant pep M5 produced in Escherichia coli. Our data strongly suggest that the mitogenic activity in M protein preparations is caused by traces of streptococcal superantigens different from M protein.

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“…M proteins (reviewed by Fischetti [20], Scott [54], and Manjula [40]) are fibrillar molecules composed of two predominantly alpha-helical protein chains arranged in a coiledcoil conformation. These dimeric molecules extend from the surface of the bacterial cell and appear as thin, hairlike projections when S. pyogenes is examined by electron microscopy (65).…”

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confidence: 99%

Environmental regulation of virulence in group A streptococci: transcription of the gene encoding M protein is stimulated by carbon dioxide

et al. 1992

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We have found that different atmospheres can have significant effects on the transcription of emm, the gene that encodes M protein, the major virulence factor of the group A streptococcus (Streptococcus pyogenes). Expression of emm was monitored by constructing a transcriptional fusion of the promoter for emm6.1 from S. pyogenes JRS4 to a promoterless chloramphenicol acetyltransferase gene. Transcription, as measured by determining chloramphenicol acetyltransferase specific activity, was stimulated by as much as 25-fold by increased carbon dioxide tension. Expression was greater in the latter stages of growth and was not affected by growth at 30 instead of 37 degrees C. Insertional inactivation of mry, a gene encoding a positive regulator of emm6.1, reduced chloramphenicol acetyltransferase activity below the detectable level. We conclude that expression of emm is influenced by environmental factors and that the level of carbon dioxide is one signal that may influence expression of M protein during infection.

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Molecular aspects of the phagocytosis resistance of group a streptococci

Cited by 12 publications

References 90 publications

Streptococcus pyogenes expressing M and M-like surface proteins are phagocytosed but survive inside human neutrophils

Streptococcus pyogenes expressing M and M-like surface proteins are phagocytosed but survive inside human neutrophils

Mitogenicity of M5 protein extracted from Streptococcus pyogenes cells is due to streptococcal pyrogenic exotoxin C and mitogenic factor MF

Environmental regulation of virulence in group A streptococci: transcription of the gene encoding M protein is stimulated by carbon dioxide

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