Cell Surface and Cytosolic Proteins of Group B Streptococcus Adding New Dimensions in Its Colonization and Pathogenesis

2020 ◽  
Author(s):  
Manju Ohri Pai ◽  
Venkatesh Srinivasa Pai ◽  
Pratima Gupta ◽  
Anuradha Chakraborti
Keyword(s):  
Cell Surface ◽  
Group B Streptococcus ◽  
Cytosolic Proteins ◽  
Group B

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 The S Protein of Group B Streptococcus Is a Critical Virulence Determinant That Impacts the Cell Surface Virulome

2021 ◽  
Vol 12 ◽  
Author(s):  
Anaamika Campeau ◽  
Satoshi Uchiyama ◽  
Concepcion Sanchez ◽  
Consuelo Sauceda ◽  
Victor Nizet ◽  
...  
Keyword(s):  
Cell Surface ◽  
Disease Burden ◽  
Group B Streptococcus ◽  
Systemic Infection ◽  
Proteome Analysis ◽  
Invasive Disease ◽  
S Protein ◽  
Virulence Determinant ◽  
Altered Cell ◽  
Group B

Group B Streptococcus (GBS, S. agalactiae) is a human commensal and occasional pathogen that remains a leading cause of neonatal sepsis and meningitis with increasing disease burden in adult populations. Although programs for universal screening in pregnancy to guide intrapartum prophylaxis have reduced GBS invasive disease burden resulting from mother-to-newborn transfer during birth, better knowledge of disease mechanisms may elucidate new strategies to reduce antibiotic exposure. In our efforts to expand the knowledge base required for targeted anti-virulence therapies, we identified a GBS homolog for a recently identified virulence determinant of group A Streptococcus, S protein, and evaluated its role in GBS pathogenesis. A GBS S protein deletion mutant, Δess, showed altered cell-surface properties compared to the WT parent strain, including defective retention of its surface polysaccharide. Quantitative proteome analysis of enzymatically shaved surface epitopes of the GBS Δess mutant revealed a dysregulated cell surface virulome, with reduced abundance of several protein and glycoprotein components. The Δess mutant showed markedly attenuated virulence in a murine model of GBS systemic infection, with increased proteasome activity detected in the spleens of animals infected with the Δess mutant. These results expand the key roles S protein plays in streptococcal pathogenesis and introduces a new GBS virulence determinant and potential target for therapy development.

scholarly journals Blood-brain barrier invasion by group B Streptococcus depends upon proper cell-surface anchoring of lipoteichoic acid

2005 ◽  
Vol 115 (9) ◽  
pp. 2499-2507 ◽  
Author(s):  
Kelly S. Doran ◽  
Erin J. Engelson ◽  
Arya Khosravi ◽  
Heather C. Maisey ◽  
Iris Fedtke ◽  
...  
Keyword(s):  
Cell Surface ◽  
Blood Brain Barrier ◽  
Group B Streptococcus ◽  
Lipoteichoic Acid ◽  
Brain Barrier ◽  
Surface Anchoring ◽  
Blood Brain ◽  
Group B

scholarly journals Molecular Dissection of the secA2 Locus of Group B Streptococcus Reveals that Glycosylation of the Srr1 LPXTG Protein Is Required for Full Virulence

2009 ◽  
Vol 191 (13) ◽  
pp. 4195-4206 ◽  
Author(s):  
Michel-Yves Mistou ◽  
Shaynoor Dramsi ◽  
Sara Brega ◽  
Claire Poyart ◽  
Patrick Trieu-Cuot
Keyword(s):  
Cell Surface ◽  
Surface Display ◽  
Group B Streptococcus ◽  
Surface Protein ◽  
Cell Surface Display ◽  
Variable Number ◽  
Bacterial Adherence ◽  
Neonatal Rat ◽  
Genes Encoding ◽  
Group B

ABSTRACT In streptococci, the secA2 locus includes genes encoding the following: (i) the accessory Sec components (SecA2, SecY2, and at least three accessory secretion proteins), (ii) two essential glycosyltranferases (GTs) (GtfA and GtfB), (iii) a variable number of dispensable additional GTs, and (iv) a secreted serine-rich LPXTG protein which is glycosylated in the cytoplasm and transported to the cell surface by this accessory Sec system. The secA2 locus of Streptococcus agalactiae strain NEM316 is structurally related to those found in other streptococci and encodes the serine-rich surface protein Srr1. We demonstrated that expression of Srr1 but not that of the SecA2 components and the associated GTs is regulated by the standalone transcriptional regulator Rga. Srr1 is synthesized as a glycosylated precursor, secreted by the SecA2 system, and anchored to the cell wall by the housekeeping sortase A. Srr1 was localized preferentially at the old poles. GtfA and/or GtfB, but not the six additional GTs, is essential for the production of Srr1. These GTs are involved in the attachment of GlcNac and sialic acid to Srr1. Full glycosylation of Srr1 is associated with the cell surface display of a protein that is more resistant to proteolytic attack. Srr1 contributes to bacterial adherence to human epithelial cell lines and virulence in a neonatal rat model. The extent of Srr1 glycosylation by GtfC to -H modulates bacterial adherence and virulence.

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 Antibody-Mediated Complement C3b/iC3b Binding to Group B Streptococcus in Paired Mother and Baby Serum Samples in a Refugee Population on the Thailand-Myanmar Border

2015 ◽  
Vol 22 (3) ◽  
pp. 319-326 ◽  
Author(s):  
Jenny Herbert ◽  
Stephen Thomas ◽  
Charlotte Brookes ◽  
Claudia Turner ◽  
Paul Turner ◽  
...  
Keyword(s):  
Cell Surface ◽  
Neonatal Sepsis ◽  
Bacterial Cell ◽  
Group B Streptococcus ◽  
Serum Samples ◽  
Carriage Rate ◽  
Content Type ◽  
Different Populations ◽  
Group B ◽  
Complement Deposition

ABSTRACTStreptococcus agalactiae(group B streptococcus [GBS]) is the leading cause of neonatal sepsis and meningitis. In this study, we determined antibody-mediated deposition of complement C3b/iC3b onto the bacterial cell surface of GBS serotypes Ia, Ib, II, III, and V. This was determined for 520 mother and umbilical cord serum sample pairs obtained at the time of birth from a population on the Thailand-Myanmar border. Antibody-mediated deposition of complement C3b/iC3b was detected to at least one serotype in 91% of mothers, despite a known carriage rate in this population of only 12%. Antibody-mediated C3b/iC3b deposition corresponded to known carriage rates, with the highest levels of complement deposition observed onto the most prevalent serotype (serotype II) followed by serotypes Ia, III, V, and Ib. Finally, neonates born to mothers carrying serotype II GBS at the time of birth showed higher antibody-mediated C3b/iC3b deposition against serotype II GBS than neonates born to mothers with no serotype II carriage. Assessment of antibody-mediated C3b/iC3b deposition against GBS may provide insights into the seroepidemiology of anti-GBS antibodies in mothers and infants in different populations.

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