Growth of group B streptococci in human serum leads to increased cell surface sialic acid and decreased activation of the alternative complement pathway

1994 ◽  
Vol 40 (2) ◽  
pp. 99-105 ◽  
Author(s):  
Mark W. Platt ◽  
Norberto Correa Jr. ◽  
Carolyn Mold
Keyword(s):  
Sialic Acid ◽  
Cell Surface ◽  
Human Serum ◽  
Group B Streptococcus ◽  
Group B Streptococci ◽  
Sialic Acid Content ◽  
Bacterial Surface ◽  
Type Iii ◽  
Alternative Complement ◽  
Group B

Group B streptococcus type III is a major cause of neonatal death. The terminal sialic acid moiety of the group B streptococcus type specific capsule has been shown to be an important virulence factor. We demonstrate here that bacteria grown in human serum have increased cell surface sialic acid content compared with cells grown in common laboratory media. This sialic acid was removed by incubation with neuraminidase, showing that it was on the bacterial surface. Serum-dependent sialylation was dependent on metabolic activity, as the addition of chloramphenicol reduced the amount of added sialic acid by more than 90%. Probing the cell surface with an antibody specific for group B streptococcus type III capsular sialic acid showed an increase in antibody binding after growth in human serum. This effect could be lowered by incubating serum-grown cells in neuraminidase prior to antibody exposure. A group B streptococcus mutant that when grown in laboratory media lacks cell surface sialic acid showed significant cell surface sialic acid when grown in human serum. This increase was associated with a significantly decreased ability to bind C3 and hence activate the alternative complement pathway.Key words: group B streptococcus, capsule, human serum.

scholarly journals Capsular Sialic Acid Limits C5a Production on Type III Group B Streptococci

1999 ◽  
Vol 67 (4) ◽  
pp. 1866-1870 ◽  
Author(s):  
Shinji Takahashi ◽  
Youko Aoyagi ◽  
Elisabeth E. Adderson ◽  
Yoshiyuki Okuwaki ◽  
John F. Bohnsack
Keyword(s):  
Sialic Acid ◽  
Specific Antibody ◽  
Acid Content ◽  
Alternative Pathway ◽  
Group B Streptococcus ◽  
Neonatal Infections ◽  
Group B Streptococci ◽  
Sialic Acid Content ◽  
Type Iii ◽  
Group B

ABSTRACT The majority of type III group B streptococcus (GBS) human neonatal infections are caused by a genetically related subgroup called III-3. We have proposed that a bacterial enzyme, C5a-ase, contributes to the pathogenesis of neonatal infections with GBS by rapidly inactivating C5a, a potent pro-inflammatory molecule, but many III-3 strains do not express C5a-ase. The amount of C5a produced in serum following incubation with representative type III strains was quantitated in order to better understand the relationship between C5a production and C5a-ase expression. C5a production following incubation of bacteria with serum depleted of antibody to the bacterial surface was inversely proportional to the sialic acid content of the bacterial capsule, with the more heavily sialylated III-3 strains generating less C5a than the less-virulent, less-sialylated III-2 strains. The amount of C5a produced correlated significantly with C3 deposition on each bacterial strain. Repletion with type-specific antibody caused increased C3b deposition and C5a production through alternative pathway activation, but C5a was functionally inactivated by strains that expressed C5a-ase. The increased virulence of III-3 strains compared to that of III-2 strains results at least partially from the higher sialic acid content of III-3 strains, which inhibits both opsonophagocytic killing and C5a production in the absence of type-specific antibody. We propose that C5a-ase is not necessary for III-3 strains to cause invasive disease because the high sialic acid content of III-3 strains inhibits C5a production.

scholarly journals Sialic acid content and surface hydrophobicity of group B streptococci

1993 ◽  
Vol 110 (1) ◽  
pp. 87-94 ◽  
Author(s):  
L. A. Teixeira ◽  
A. M. S. Figueiredo ◽  
B. T. Ferreira ◽  
V. M. L. Alves ◽  
P. E. Nagao ◽  
...  
Keyword(s):  
Sialic Acid ◽  
Cell Surface ◽  
Acid Content ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Gas Liquid Chromatography ◽  
Group B Streptococci ◽  
Sialic Acid Content ◽  
Asymptomatic Patients ◽  
Group B

SUMMARYThe sialic acid content and the cell-surface hydrophobicity index of 40 group B streptococci (GBS) strains were assessed. GBS isolated from invasive infections (virulent strains) presented an increased level of sialic acid content (1.4%) when compared with GBS isolated from asymptomatic patients (0.53%). Treatment of GBS strain 85634 with neuraminidase resulted in a decrease (about 25%) in the net negative surface charge as assessed by cell electrophoresis. This finding suggests that sialic acid residues are important anionogenic groups exposed on GBS cell surface.N-acetylneuraminic acid was the only sialic acid derivative characterized in the strain 85634 as evaluated by gas-liquid chromatography. GBS from different serotypes presented a hydrophobic index mean value of 0.9. Even though the sialic acid contributed effectively to the negative charge on GBS cell surface, no difference was observed in the hydrophobic index when virulent and avirulent strains were compared.

scholarly journals Sialylation of Group B Streptococcal Capsular Polysaccharide Is Mediated by cpsK and Is Required for Optimal Capsule Polymerization and Expression

2005 ◽  
Vol 187 (13) ◽  
pp. 4615-4626 ◽  
Author(s):  
D. O. Chaffin ◽  
L. M. Mentele ◽  
C. E. Rubens
Keyword(s):  
Sialic Acid ◽  
Cell Surface ◽  
High Performance ◽  
Capsular Polysaccharide ◽  
Immunoblot Analysis ◽  
Enzyme Linked Immunosorbent Assay ◽  
Group B Streptococci ◽  
Type Iii ◽  
Self Recognition ◽  
Group B

ABSTRACT Several bacterial pathogens have evolved the means to escape immune detection by mimicking host cell surface carbohydrates that are crucial for self/non-self recognition. Sialic acid, a terminal residue on these carbohydrates, inhibits activation of the alternate pathway of complement by recruiting the immune modulating molecule factors H, I, and iC3b. Sialylation of capsular polysaccharide (CPS) is important for virulence of group B streptococci (GBS), a significant human pathogen. We previously reported that cpsK, a gene within the cps locus of type III GBS, could complement a sialyltransferase deficient lst mutant of Haemophilus ducreyi, implicating its role in sialylation of the GBS capsule. To explore the function of cpsK in GBS capsule production, we created a mutant in cpsK. Immunoblot analysis and enzyme-linked immunosorbent assay using anti-type III CPS antisera demonstrated that the mutant CPS did not contain sialic acid. This was confirmed by high-performance liquid chromatography after mild acid hydrolysis of the CPS. Although increased CPS chain length was seen for this strain, CPS production was <20% of the parental isolate. An episomal cpsK copy restored synthesis of sialo-CPS to wild-type levels. These data support our hypothesis that cpsK encodes the GBS CPS sialyltransferase and provide further evidence that lack of CPS oligosaccharide sialylation reduces the amount of CPS expressed on the cell surface. These observations also imply that one or more of the components involved in synthesis or transport of oligosaccharide repeating units requires a sialo-oligosaccharide for complete activity.

Colonization With Group B Streptococci in Girls Under 16 Years of Age

PEDIATRICS ◽  
1977 ◽  
Vol 60 (4) ◽  
pp. 473-476 ◽  
Author(s):  
Margaret R. Hammerschlag ◽  
Carol J. Baker ◽  
Susan Alpert ◽  
Dennis L. Kasper ◽  
Ingrid Rosner ◽  
...  
Keyword(s):  
Anal Canal ◽  
Serum Antibody ◽  
Group B Streptococcus ◽  
Group B Streptococci ◽  
Capsular Antigen ◽  
Type Iii ◽  
Group B

Cultures from the vagina, pharynx, and anal canal of 100 healthy girls, 2 months through 15 years of age, were examined for the presence of group B streptococci. Of the 100 participants, 20% were colonized at one or more of these three sites. Pharyngeal colonization was detected in 15% of the girls under 11 years of age and in 5% of those over 11 years of age. Colonization at anogenital sites was observed in 19% of participants under 3 years of age, in 25% of those 11 years of age and older, and in only 4% of those between the ages of 3 and 10 years (P &lt; .025). The concentration of serum antibody directed against the polysaccharide capsular antigen isolated from type III, group B Streptococcus appeared, in part, to be related to increasing age.

scholarly journals Subtractive Hybridization Identifies a Novel Predicted Protein Mediating Epithelial Cell Invasion by Virulent Serotype III Group B Streptococcus agalactiae

2003 ◽  
Vol 71 (12) ◽  
pp. 6857-6863 ◽  
Author(s):  
Elisabeth E. Adderson ◽  
Shinji Takahashi ◽  
Yan Wang ◽  
Jianling Armstrong ◽  
Dylan V. Miller ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Streptococcus Agalactiae ◽  
Group B Streptococcus ◽  
Newborn Infants ◽  
Subtractive Hybridization ◽  
Group B Streptococci ◽  
Mutant Type ◽  
Isogenic Mutant ◽  
Type Iii ◽  
Group B

ABSTRACT Group B Streptococcus agalactiae bacteria (group B streptococci [GBS]) are the most common cause of serious bacterial infection in newborn infants. The majority of serotype III-related cases of neonatal disease are caused by a genetically related subgroup of bacteria, restriction fragment digest pattern (RDP) type III-3, suggesting that these strains possess unique genes contributing to virulence. We used genomic subtractive hybridization to identify regions of genomic DNA unique to virulent RDP type III-3 GBS strains. Within one of these III-3-specific regions is a 1,506-bp open reading frame, spb1 (surface protein of group B streptococcus 1). A mutant type III GBS strain lacking Spb1 was constructed in virulent RDP type III-3 strain 874391, and the interactions of the wild-type and spb1 isogenic mutant with a variety of epithelial cells important to GBS colonization and infection were compared. While adherence of the spb1 isogenic mutant to A549 respiratory, C2Bbe1 colonic, and HeLa cervical epithelial cells was slightly lower than that of the 874391 strain, invasion of the Spb1− mutant was significantly reduced with these cell lines compared to what was seen with 874391. The defect in epithelial invasion was corrected by supplying spb1 in trans. These observations suggest that Spb1 contributes to the pathogenesis of neonatal GBS infection by mediating internalization of virulent serotype III GBS and confirm that understanding of the population structure of bacteria may lead to insights into the pathogenesis of human infections.

scholarly journals NeuA Sialic Acid O-Acetylesterase Activity Modulates O-Acetylation of Capsular Polysaccharide in Group B Streptococcus

2007 ◽  
Vol 282 (38) ◽  
pp. 27562-27571 ◽  
Author(s):  
Amanda L. Lewis ◽  
Hongzhi Cao ◽  
Silpa K. Patel ◽  
Sandra Diaz ◽  
Wesley Ryan ◽  
...  
Keyword(s):  
Sialic Acid ◽  
Capsular Polysaccharide ◽  
Group B Streptococcus ◽  
Site Directed Mutagenesis ◽  
Synthetase Activity ◽  
Bacterial Surface ◽  
Acetylneuraminic Acid ◽  
Single Polypeptide ◽  
Group B

Group B Streptococcus (GBS) is a common cause of neonatal sepsis and meningitis. A major GBS virulence determinant is its sialic acid (Sia)-capped capsular polysaccharide. Recently, we discovered the presence and genetic basis of capsular Sia O-acetylation in GBS. We now characterize a GBS Sia O-acetylesterase that modulates the degree of GBS surface O-acetylation. The GBS Sia O-acetylesterase operates cooperatively with the GBS CMP-Sia synthetase, both part of a single polypeptide encoded by the neuA gene. NeuA de-O-acetylation of free 9-O-acetyl-N-acetylneuraminic acid (Neu5,9Ac2) was enhanced by CTP and Mg2+, the substrate and co-factor, respectively, of the N-terminal GBS CMP-Sia synthetase domain. In contrast, the homologous bifunctional NeuA esterase from Escherichia coli K1 did not display cofactor dependence. Further analyses showed that in vitro, GBS NeuA can operate via two alternate enzymatic pathways: de-O-acetylation of Neu5,9Ac2 followed by CMP activation of Neu5Ac or activation of Neu5,9Ac2 followed by de-O-acetylation of CMP-Neu5,9Ac2. Consistent with in vitro esterase assays, genetic deletion of GBS neuA led to accumulation of intracellular O-acetylated Sias, and overexpression of GBS NeuA reduced O-acetylation of Sias on the bacterial surface. Site-directed mutagenesis of conserved asparagine residue 301 abolished esterase activity but preserved CMP-Sia synthetase activity, as evidenced by hyper-O-acetylation of capsular polysaccharide Sias on GBS expressing only the N301A NeuA allele. These studies demonstrate a novel mechanism regulating the extent of capsular Sia O-acetylation in intact bacteria and provide a genetic strategy for manipulating GBS O-acetylation in order to explore the role of this modification in GBS pathogenesis and immunogenicity.

scholarly journals Protein rib: a novel group B streptococcal cell surface protein that confers protective immunity and is expressed by most strains causing invasive infections.

1993 ◽  
Vol 177 (6) ◽  
pp. 1593-1603 ◽  
Author(s):  
M Stålhammar-Carlemalm ◽  
L Stenberg ◽  
G Lindahl
Keyword(s):  
Cell Surface ◽  
Protective Immunity ◽  
Group B Streptococcus ◽  
Rabbit Antiserum ◽  
Surface Protein ◽  
Amino Acid Sequences ◽  
Cell Surface Protein ◽  
Type Iii ◽  
Invasive Infections ◽  
Group B

The group B Streptococcus, an important cause of invasive infections in the neonate, is classified into four major serotypes (Ia, Ib, II, and III) based on the structure of the polysaccharide capsule. Since the capsule is a known virulence factor, it has been extensively studied, in particular in type III strains, which cause the majority of invasive infections. Two cell surface proteins, alpha and beta, have also been studied in detail since they confer protective immunity, but these proteins are usually not expressed by type III strains. We describe here a cell surface protein, designated protein Rib (resistance to proteases, immunity, group B), that confers protective immunity and is expressed by most strains of type III. Protein Rib was first identified as a distinct 95-kD protein in extracts of a type III strain, and was purified to homogeneity from that strain. Rabbit antiserum to protein Rib was used to demonstrate that it is expressed on the cell surface of 31 out of 33 type III strains, but only on 1 out of 25 strains representing the other three serotypes. Mouse protection tests showed that antiserum to protein Rib protects against lethal infection with three different strains expressing this antigen, including a strain representing a recently identified high virulence type III clone. Protein Rib is immunologically unrelated to the alpha and beta proteins, but shares several features with the alpha protein. Most importantly, the NH2-terminal amino acid sequences of the Rib and alpha proteins are identical at 6 out of 12 positions. In addition, both protein Rib and the alpha protein are relatively resistant to trypsin (and Rib is also resistant to pepsin) and both proteins vary greatly in size between different clinical isolates. Finally, both protein Rib and the alpha protein exhibit a regular ladderlike pattern in immunoblotting experiments, which may reflect a repetitive structure. Taken together, these data suggest that the Rib and alpha proteins are members of a family of proteins with related structure and function. Since protein Rib confers protective immunity, it may be valuable for the development of a protein vaccine against the group B Streptococcus, an encapsulated bacterium.

scholarly journals Estimation of Group B Streptococcus Type III Polysaccharide-Specific Antibody Concentrations in Human Sera Is Antigen Dependent

1998 ◽  
Vol 66 (12) ◽  
pp. 5848-5853 ◽  
Author(s):  
Reva Bhushan ◽  
Bascom F. Anthony ◽  
Carl E. Frasch
Keyword(s):  
Human Serum Albumin ◽  
Serum Albumin ◽  
Human Serum ◽  
Conjugate Vaccine ◽  
Group B Streptococcus ◽  
Antigenic Specificity ◽  
Enzyme Linked Immunosorbent Assay ◽  
Type Iii ◽  
Human Sera ◽  
Group B

ABSTRACT The presence of immunoglobulin G (IgG) antibodies against group B streptococcus (GBS) type III polysaccharide (PS) has been correlated with protection against GBS disease. The GBS type III PS is structurally similar to the pneumococcal type 14 PS, differing only in the presence of sialic acid residues. Four different preparations of GBS type III PS were evaluated for their specificity in enzyme-linked immunosorbent assay (ELISA): free PS, free PS mixed with methylated human serum albumin (mHSA), PS conjugated to biotin and PS conjugated to human serum albumin. Three groups of human sera were used to evaluate these PS preparations: sera from recipients of a GBS PS vaccine, sera from women receiving a GBS type III PS-tetanus toxoid conjugate vaccine, and sera from nonimmunized healthy women of childbearing age. Estimated antibody concentrations were different depending on the PS preparation used. Using any of the four preparations, we were able to measure ≤0.05 μg of IgG antibody to the GBS type III PS per ml. The specificity of the assay was determined by competitive inhibition with homologous and heterologous PS. The pneumococcal type 14 PS did not inhibit binding of antibody to the native GBS type III PS in sera from adults receiving the GBS PS vaccine or in sera from nonimmunized adults (except serum G9). The pneumococcal type 14 PS inhibited 50% in sera from recipients of GBS type III conjugate vaccine and in serum G9 when GBS type III PS conjugated to biotin or to HSA was used as antigen in ELISA. These data show that free GBS type III PS or PS mixed with mHSA is a sensitive and specific antigen for ELISA and that conjugation can alter the antigenic specificity of a PS.

Role of Antibody to Native Type III Polysaccharide of Group B Streptococcus in Infant Infection

PEDIATRICS ◽  
1981 ◽  
Vol 68 (4) ◽  
pp. 544-549 ◽  
Author(s):  
Carol J. Baker ◽  
Morven S. Edwards ◽  
Dennis L. Kasper
Keyword(s):  
Group B Streptococcus ◽  
Systemic Infection ◽  
Group B Streptococci ◽  
Symptomatic Infection ◽  
Type Iii ◽  
Vaginal Colonization ◽  
Low Levels ◽  
Group B ◽  
Antibody Levels

The role of maternally acquired antibody to native type III polysacchande of group B Streptococcus as a determinant of susceptibility for infant systemic infection was investigated. Sera from 11 1 acutely ill infants with type III group B streptococcal bacteremia and/or meningitis and their mothers, and cord sera from 45 healthy neonates and their mothers who had type III group B streptococcal vaginal colonization at delivery were studied. Sera from each of 111 acutely ill infants contained very low levels ofantibody (sjlt 1.7 µg/ml, median 0.4 µg/ml), and a significant correlation with maternal levels was tested for early onset infection (median 0.6 µg/ml; r = .76; P sjlt .01). Women whose infants remained well had antibody levels sjgt 2 µg/ml in their sera (73%) more often than those whose infants developed symptomatic infection (17%) (P sjlt .001), and the median level in their sera (12.6 µg/ml) was considerably higher. Study of sera obtained during convalescence from 86 surviving infants indicated a poor antibody response to infection. In contrast, high levels of antibody were detected in sera from each of five convalescent women with postpartum bacteremia. These data extend earlier observations suggesting the correlation between low levels of type-specific antibody in serum and risk for systemic infection with type III strains of group B streptococci.

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