scholarly journals Cytotoxic Effects of Streptolysin O and Streptolysin S Enhance the Virulence of Poorly Encapsulated Group A Streptococci

2003 ◽  
Vol 71 (1) ◽  
pp. 446-455 ◽  
Author(s):  
Gabriele Sierig ◽  
Colette Cywes ◽  
Michael R. Wessels ◽  
Cameron D. Ashbaugh
Keyword(s):  
Bacterial Resistance ◽  
Cell Injury ◽  
Natural Infection ◽  
Group A Streptococci ◽  
Cytotoxic Effects ◽  
In Vivo Models ◽  
Streptolysin S ◽  
Streptolysin O ◽  
Group A

ABSTRACT Although the toxicity of streptolysin O (SLO) and streptolysin S (SLS) in purified group A streptococci (GAS) has been established, the effect of these molecules in natural infection is not well understood. To identify whether biologically relevant concentrations of SLO and SLS were cytotoxic to epithelial and phagocytic cells that the bacteria would typically encounter during human infection and to characterize the influence of cell injury on bacterial pathogenesis, we derived GAS strains deficient in SLO or SLS in the background of an invasive GAS M3 isolate and determined their virulence in in vitro and in vivo models of human disease. Whereas bacterial production of SLO resulted in lysis of both human keratinocytes and polymorphonuclear leukocytes, GAS expression of SLS was associated only with keratinocyte injury. Expression of SLO but not SLS impaired polymorphonuclear leukocyte killing of GAS in vitro, but this effect could only be demonstrated in the background of acapsular organisms. In mouse invasive soft-tissue infection, neither SLO or SLS expression significantly influenced mouse survival. By contrast, in a mouse model of bacterial sepsis after intraperitoneal inoculation of GAS, SLO expression enhanced the virulence of both encapsulated and acapsular GAS, whereas SLS expression increased the virulence only of acapsular GAS. We conclude that the cytotoxic effects of SLO protect GAS from phagocytic killing and enhance bacterial virulence, particularly of strains that may be relatively deficient in hyaluronic acid capsule. Compared to SLO, SLS in this strain background has a more modest influence on GAS pathogenicity and the effect does not appear to involve bacterial resistance to phagocytosis.

scholarly journals Antibodies against a Synthetic Peptide of SagA Neutralize the Cytolytic Activity of Streptolysin S from Group A Streptococci

2002 ◽  
Vol 70 (4) ◽  
pp. 2166-2170 ◽  
Author(s):  
James B. Dale ◽  
Edna Y. Chiang ◽  
David L. Hasty ◽  
Harry S. Courtney
Keyword(s):  
Synthetic Peptide ◽  
Neutralizing Antibodies ◽  
Natural Infection ◽  
Convincing Evidence ◽  
Cytolytic Activity ◽  
M Protein ◽  
Group A Streptococci ◽  
Streptolysin S ◽  
Group A

ABSTRACT Virtually all group A streptococci (GAS) produce streptolysin S (SLS), a cytolytic toxin that is responsible for the beta-hemolysis surrounding colonies of the organisms grown on blood agar. SLS is an important virulence determinant of GAS, and recent studies have identified a nine-gene locus that is responsible for synthesis and transport of the toxin. SLS is not immunogenic; thus, no neutralizing antibodies are evoked during the course of natural infection. In the present study, we show that a synthetic peptide containing amino acid residues 10 to 30 of the putative SLS (SagA) propeptide [SLS(10-30)] coupled to keyhole limpet hemocyanin evoked antibodies in rabbits that completely neutralized the hemolytic activity of the toxin in vitro. Inhibition of hemolysis was reversed by preincubation of the immune serum with soluble, unconjugated peptide, indicating the specificity of the antibodies. In addition, antibodies that were affinity purified over an SLS(10-30) peptide column completely inhibited SLS-mediated hemolysis. The SLS(10-30) antisera did not opsonize group A streptococci; however, when combined with type-specific M protein antisera, the SLS antibodies significantly enhanced phagocytosis mediated by M protein antibodies. Thus, we have shown for the first time that it is possible to raise neutralizing antibodies against one of the most potent bacterial cytolytic toxins known. Our data also provide convincing evidence that the sagA gene actually encodes the SLS peptide of GAS. The synthetic peptide may prove to be an important component of vaccines designed to prevent GAS infections.

scholarly journals Role of NADase in Virulence in Experimental Invasive Group A Streptococcal Infection

2005 ◽  
Vol 73 (10) ◽  
pp. 6562-6566 ◽  
Author(s):  
Angela L. Bricker ◽  
Vincent J. Carey ◽  
Michael R. Wessels
Keyword(s):  
Human Infection ◽  
Host Animal ◽  
Cytotoxic Effects ◽  
Invasive Group ◽  
Streptolysin O ◽  
Group A ◽  
Wild Type Parent

ABSTRACT Group A streptococci (GAS) produce several exoproteins that are thought to contribute to the pathogenesis of human infection. Two such proteins, streptolysin O (SLO) and NAD+-glycohydrolase (NADase), have been shown to interact functionally as a compound signaling toxin. When GAS are bound to the surface of epithelial cells in vitro, SLO forms pores in the cell membrane and delivers NADase to the epithelial cell cytoplasm. In vitro, intoxication of keratinocytes with NADase is associated with cytotoxic effects and induction of apoptosis; however, the importance of NADase during infection of an animal host has not been established. We employed isogenic GAS mutants to assess the contribution of NADase activity to GAS virulence in vivo using mouse models of invasive soft-tissue infection and septicemia. In both models, mutant GAS that lacked NADase activity were significantly attenuated for virulence compared with the isogenic wild-type parent, confirming an important role for NADase in the infection of a host animal. A double mutant lacking SLO and NADase activity had an intermediate virulence phenotype, consistent with the hypothesis that SLO evokes a protective innate immune response. We conclude that NADase and SLO together enhance GAS virulence in vivo.

scholarly journals The streptolysins of various groups and types of haemolytic streptococci; a serological investigation

1939 ◽  
Vol 39 (1) ◽  
pp. 1-11 ◽  
Author(s):  
E. W. Todd
Keyword(s):  
Streptolysin S ◽  
Serological Investigation ◽  
Streptolysin O ◽  
Oxygen Sensitive ◽  
Group A

1. Group A haemolytic streptococci produce two distinct varieties of streptolysin:(a) Streptolysin O which is oxygen sensitive.(b) Streptolysin S which is serum extractable.These two streptolysins are neutralized by separate antibodies which appear to be entirely unrelated.2. Neutralization experiments in vitro with group A antistreptolysin O show that streptolysin O is formed by strains belonging to groups A, C (human) and G; it is not formed by strains belonging to groups B, C (animal), D, E, H and K. The relation of group F strains to streptolysin O is at present uncertain.3. Group A strains of different serological types all produce streptolysin S neutralizable by group A antistreptolysin S. Strains belonging to groups B, C, D, E, F, G, H and K do not produce streptolysin S neutralizable by group A antistreptolysin S. The neutralization is therefore group-specific but not type-specific.

scholarly journals Reduced Virulence of Group A Streptococcal Tn916 Mutants That Do Not Produce Streptolysin S

1998 ◽  
Vol 66 (4) ◽  
pp. 1671-1679 ◽  
Author(s):  
Stephen D. Betschel ◽  
Sergio M. Borgia ◽  
Neil L. Barg ◽  
Donald E. Low ◽  
Joyce C. S. De Azavedo
Keyword(s):  
Promoter Region ◽  
Open Reading Frame ◽  
Donor Strain ◽  
Group A Streptococci ◽  
Wild Type ◽  
Reading Frame ◽  
Streptolysin S ◽  
Streptolysin O ◽  
Group A ◽  
Type Strains

ABSTRACT Streptolysin S (SLS) is a potent cytolytic toxin produced by nearly all group A streptococci (GAS). SLS-deficient Tn916insertional mutants were generated from two clinical isolates of GAS, MGAS166s and T18Ps (M serotypes 1 and 18, respectively), by transposon mutagenesis using Tn916 donor strain Enterococcus faecalis CG110. Representative nonhemolytic transconjugants SBNH5 and SB30-2 each harbored a single Tn916 insertion in identical loci. The insertion in SBNH5 was located in the promoter region of an open reading frame, designated sagA, rendering it transcriptionally inactive. Protease, streptolysin O, and DNase activities and the production of M protein remained the same in the nonhemolytic mutants and the wild-type strains, as did the growth rates and exoprotein profiles. Transconjugants were evaluated in an established murine model by injecting the organisms subcutaneously and monitoring the mice for alterations in weight and the development of necrotic lesions. Animals infected with SBNH5, compared to those infected with MGAS166s, gained weight during the first 24 h (+1.15 versus −1.16 g; P < 0.05) and had fewer necrotic lesions (0 versus 7; P = 0.0007). Animals infected with SB30-2, compared to those infected with T18Ps, also gained weight within the first 24 h (+0.54 versus −0.66 g; P< 0.05) and produced fewer necrotic lesions (1 versus 8;P = 0.001). Revertants of the mutants in which Tn916 had been excised regained the hemolytic phenotype and the virulence profile of the wild-type strains. This study demonstrates that SLS-deficient mutants of GAS, belonging to different M serotypes and containing identical Tn916 mutations, are markedly less virulent than their isogenic parents.

scholarly journals Cytotoxic Effects In Vitro of Highly Purified Streptolysin O on Mouse Macrophages Cultured in a Serum-Free Medium

1966 ◽  
Vol 92 (4) ◽  
pp. 1150-1153 ◽  
Author(s):  
Robert M. Fauve ◽  
Joseph E. Alouf ◽  
Albert Delaunay ◽  
Marcel Raynaud
Keyword(s):  
Serum Free Medium ◽  
Free Medium ◽  
Cytotoxic Effects ◽  
Serum Free ◽  
Streptolysin O ◽  
Mouse Macrophages

scholarly journals THE ANTISTREPTOCOCCAL PROPERTY OF MILK

1952 ◽  
Vol 95 (1) ◽  
pp. 25-38 ◽  
Author(s):  
Armine T. Wilson ◽  
Herman Rosenblum
Keyword(s):  
Goat Milk ◽  
Cow Milk ◽  
Group A Streptococci ◽  
Highly Sensitive ◽  
Group A ◽  
Resistant Strains ◽  
Intermediate Degree

The measurement in vitro of lactenin, the antistreptococcal substance of milk, is affected by the size of the inoculum, the temperature of incubation, and the type of medium employed. Hemolytic streptococci belonging to the several serological groups vary in susceptibility to lactenin. All group A streptococci, regardless of type, are highly sensitive to it, and milk receiving a small inoculum sterilizes itself within 48 hours or less. By contrast, most strains of groups B, C, D, and E, although they may temporarily be inhibited, ultimately achieve full growth. Strains belonging to groups F, G, H, K, and L vary in sensitivity, some being fully inhibited and others achieving full growth. When streaked on the surface of milk-agar plates and examined at the end of 24 hours the streptococci fall into two classes: sensitive strains which do not produce visible colonies on the plate, and resistant strains which grow excellently. Very few strains show an intermediate degree of sensitivity. Human and goat milk contain an antistreptococcal principle which appears to be the same as the lactenin of cow milk, since streptococci which are inhibited by milk from one species are inhibited by milk from the others, and vice versa.

scholarly journals Inhibition of β-haemolysis by opacity factor in group A streptococci

1977 ◽  
Vol 78 (3) ◽  
pp. 355-362 ◽  
Author(s):  
Alison M. Pinney ◽  
Jean P. Widdowson ◽  
W. R. Maxted
Keyword(s):  
Ribonucleic Acid ◽  
Horse Serum ◽  
Blood Agar ◽  
Group A Streptococci ◽  
Streptolysin S ◽  
Group A ◽  
Horse Blood

SUMMARYGroup-A streptococci belonging to opacity-factor (OF)-positive M types were poorly haemolytic on horse-blood agar, but members of OF-negative M types, and M-negative variants of OF-positive strains gave good haemolysis. Horse-serum extracts of strains of OF-negative serotypes 6 and 12, and M-negative variant cultures of OF-positive serotypes 4 and 49, had higher titres of streptolysin S than did similar extracts of OF-positive, M-positive cultures of types 4 and 49. However, much larger amounts of streptolysin S could be extracted with ribonuclease (RNAase)-digested yeast ribonucleic acid (RNA) and M-positive OF-positive cultures treated in this way gave extracts at least as strong as did their M-negative variants or the OF-negative strains. Extraction of streptolysin S from OF-negative strains by serum could be inhibited by previous incubation of the serum with extracellular OF, suggesting that the production of diffusable OF by M-positive variants of OF-positive serotypes interferes with the extraction of streptolysin S by serum and leads to poor haemolysis on blood agar.The haemolysis of all strains on blood agar was greatly improved by the incorporation of 0·1% (w/v) RNAase-digested yeast RNA into the medium, but the improvement was most marked in OF-positive serotypes.

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