scholarly journals The Effects of PspC on Complement-Mediated Immunity to Streptococcus pneumoniae Vary with Strain Background and Capsular Serotype

2009 ◽  
Vol 78 (1) ◽  
pp. 283-292 ◽  
Author(s):  
Jose Yuste ◽  
Suneeta Khandavilli ◽  
Naadir Ansari ◽  
Kairya Muttardi ◽  
Laura Ismail ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Allelic Variation ◽  
Degradation Products ◽  
Alternative Pathway ◽  
Surface Protein ◽  
Immunoblot Analysis ◽  
Factor H ◽  
Negative Regulator ◽  
Complement Activity ◽  
Strain Background

ABSTRACT Streptococcus pneumoniae may evade complement activity by binding of factor H (FH), a negative regulator of the alternative pathway, to the surface protein PspC. However, existing data on the effects of FH binding to PspC on complement activity are conflicting, and there is also considerable allelic variation in PspC structure between S. pneumoniae strains that may influence PspC-dependent effects on complement. We have investigated interactions with complement for several S. pneumoniae strains in which the gene encoding PspC has been deleted. The degree of FH binding varied between strains and was entirely dependent on PspC for seven strains. Data obtained with TIGR4 strains expressing different capsular serotypes suggest that FH binding is affected by capsular serotype. Results of immunoblot analysis for C3 degradation products and iC3b deposition assays suggested that FH bound to PspC retained functional activity, but loss of PspC had strikingly varied effects on C3b/iC3b deposition on S. pneumoniae, with large increases on serotype 4, 6A, 6B, and 9V strains but only small increases or even decreases on serotype 2, 3, 17, and 23F strains. Repeating C3b/iC3b assays with TIGR4 strains expressing different capsular serotypes suggested that differences in the effect of PspC on C3b/iC3b deposition were largely independent of capsular serotype and depend on strain background. However, data obtained from infection in complement-deficient mice demonstrated that differences between strains in the effects of PspC on complement surprisingly did not influence the development of septicemia.

scholarly journals The Human Complement Regulator Factor H Binds Pneumococcal Surface Protein PspC via Short Consensus Repeats 13 to 15

2002 ◽  
Vol 70 (10) ◽  
pp. 5604-5611 ◽  
Author(s):  
Thomas G. Duthy ◽  
Rebecca J. Ormsby ◽  
Eleni Giannakis ◽  
A. David Ogunniyi ◽  
Uwe H. Stroeher ◽  
...  
Keyword(s):  
Alternative Pathway ◽  
Regulatory System ◽  
Surface Protein ◽  
Fluid Phase ◽  
Direct Consequence ◽  
Factor H ◽  
Negative Regulator ◽  
Short Consensus Repeats ◽  
High Concentrations ◽  
Complement Regulator

ABSTRACT The innate ability of Streptococcus pneumoniae to resist complement activation and complement-mediated phagocytosis may be a direct consequence of the ability of the bacteria to bind components of the complement regulatory system. One such component, factor H (fH), is a crucial fluid-phase negative regulator of the alternative pathway of complement and is utilized by a number of pathogenic organisms to resist complement attack. The pneumococcal surface protein C (PspC [also known as CbpA] and SpsA) has been shown to bind fH, although the exact binding site within one or more of the 20 short consensus repeats (SCRs) of the molecule is not known. The purpose of the current study was to map specific SCRs on fH responsible for this binding. Initial experiments utilizing type 2 pneumococcal strain D39 and its isogenic PspC-negative derivative (D39/pspC mutant) showed that fH binding was PspC dependent. A purified recombinant protein derivative of PspC that lacked the proline-rich region (PspCΔPro) had a reduced binding efficiency for fH, thereby directly showing the importance of this region for the fH interaction. We have specifically shown by inhibition experiments that SCRs responsible for heparin and C3b binding of fH are not involved in binding PspC and the interaction between fH and PspC is largely hydrophobic, since no inhibition was observed in the presence of high concentrations of NaCl. Construction of SCR proteins encompassing the whole fH molecule showed that SCRs 8 to 15 (SCR 8-15) mediated binding to PspC. Further localization experiments revealed that SCR 13 and SCR 15 were required for full binding, although partial binding was retained when either SCR was removed.

scholarly journals Cross-Reactivity of Antipneumococcal Surface Protein C (PspC) Antibodies with Different Strains and Evaluation of Inhibition of Human Complement Factor H and Secretory IgA Binding via PspC

2012 ◽  
Vol 19 (4) ◽  
pp. 499-507 ◽  
Author(s):  
Adriana T. Moreno ◽  
Maria Leonor S. Oliveira ◽  
Paulo L. Ho ◽  
Cintia F. M. Vadesilho ◽  
Giovana M. P. Palma ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Western Blotting ◽  
Protein C ◽  
Alternative Pathway ◽  
Surface Protein ◽  
Cross Reactivity ◽  
Factor H ◽  
Secretory Iga ◽  
Complement Factor ◽  
Cell Extracts

ABSTRACTPneumococcal surface protein C (PspC) is an important candidate for a cost-effective vaccine with broad coverage against pneumococcal diseases. Previous studies have shown thatStreptococcus pneumoniaeis able to bind to both human factor H (FH), an inhibitor of complement alternative pathway, and human secretory IgA (sIgA) via PspC. PspC was classified into 11 groups based on variations of the gene. In this work, we used three PspC fragments from different groups (PspC3, PspC5, and PspC8) to immunize mice for the production of antibodies. Immunization with PspC3 induced antibodies that recognized the majority of the clinical isolates as analyzed by Western blotting of whole-cell extracts and flow cytometry of intact bacteria, while anti-PspC5 antibodies showed cross-reactivity with the paralogue pneumococcal surface protein A (PspA), and anti-PspC8 antibodies reacted only with the PspC8-expressing strain. Most of the isolates tested showed strong binding to FH and weaker interaction with sIgA. Preincubation with anti-PspC3 and anti-PspC5 IgG led to some inhibition of binding of FH, and preincubation with anti-PspC3 partially inhibited sIgA binding in Western blotting. The analysis of intact bacteria through flow cytometry showed only a small decrease in FH binding after incubation of strain D39 with anti-PspC3 IgG, and one clinical isolate showed inhibition of sIgA binding by anti-PspC3 IgG. We conclude that although anti-PspC3 antibodies were able to recognize PspC variants from the majority of the strains tested, partial inhibition of FH and sIgA binding through anti-PspC3 antibodiesin vitrocould be observed for only a restricted number of isolates.

scholarly journals Antigenic Variation inStreptococcus pneumoniaePspC Promotes Immune Escape in the Presence of Variant-Specific Immunity

mBio ◽  
2018 ◽  
Vol 9 (2) ◽  
Author(s):  
M. Georgieva ◽  
L. Kagedan ◽  
Ying-Jie Lu ◽  
C. M. Thompson ◽  
M. Lipsitch
Keyword(s):  
Streptococcus Pneumoniae ◽  
Sequence Variation ◽  
Antigenic Variation ◽  
Biological Function ◽  
Immune Escape ◽  
Surface Protein ◽  
Factor H ◽  
Sequence Diversity ◽  
Protein Antigens ◽  
Specific Immunity

ABSTRACTGenomic analysis reveals extensive sequence variation and hot spots of recombination in surface proteins ofStreptococcus pneumoniae. While this phenomenon is commonly attributed to diversifying selection by host immune responses, there is little mechanistic evidence for the hypothesis that diversification of surface protein antigens produces an immune escape benefit during infection withS. pneumoniae. Here, we investigate the biological significance of sequence variation within theS. pneumoniaecell wall-associated pneumococcal surface protein C (PspC) protein antigen. UsingpspCallelic diversity observed in a large pneumococcal collection, we produced variant-specific protein constructs that span the sequence variability within thepspClocus. We show that antibodies raised against these PspC constructs are variant specific and prevent association between PspC and the complement pathway mediator, human factor H. We found that PspC variants differ in their capacity to bind factor H, suggesting that sequence variation withinpspCreflects differences in biological function. Finally, in an antibody-dependent opsonophagocytic assay,S. pneumoniaeexpressing a PspC variant matching the antibody specificity was killed efficiently. In contrast, killing efficacy was not evident againstS. pneumoniaeexpressing mismatched PspC variants. Our data suggest that antigenic variation within the PspC antigen promotes immune evasion and could confer a fitness benefit during infection.IMPORTANCELoci encoding surface protein antigens inStreptococcus pneumoniaeare highly polymorphic. It has become a truism that these polymorphisms are the outcome of selective pressure onS. pneumoniaeto escape host immunity. However, there is little mechanistic evidence to support the hypothesis that diversifying protein antigens produces a benefit for the bacteria. Using the highly diversepspClocus, we have now characterized the functional and immune implications of sequence diversity within the PspC protein. We have characterized the spectrum of biological function among diverse PspC variants and show thatpspCsequence diversity reflects functional differences. Further, we show that sequence variation in PspC confers an immune escape benefit in the presence of anti-PspC variant-specific immunity. Overall, the results of our studies provide insights into the functional implications of protein sequence diversity and the role of variant-specific immunity in its maintenance.

scholarly journals PspK of Streptococcus pneumoniae Increases Adherence to Epithelial Cells and Enhances Nasopharyngeal Colonization

2012 ◽  
Vol 81 (1) ◽  
pp. 173-181 ◽  
Author(s):  
L. E. Keller ◽  
C. V. Jones ◽  
J. A. Thornton ◽  
M. E. Sanders ◽  
E. Swiatlo ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Epithelial Cells ◽  
Immunoglobulin A ◽  
Surface Protein ◽  
Invasive Disease ◽  
Factor H ◽  
Host Cells ◽  
Content Type ◽  
Capsule Locus ◽  
Complement Regulator

Streptococcus pneumoniae(the pneumococcus) colonizes the human nasopharynx and can cause invasive disease aided by the pneumococcal capsule. Group II nontypeableS. pneumoniae(NTSp) lacks a polysaccharide capsule, and a subgroup of NTSp carriage isolates has been found to have a novel gene, pneumococcal surface protein K (pspK), which replaces the capsule locus. A recent rise in the number of NTSp isolates colonizing the human nasopharynx has been observed, but the colonization factors of NTSp have not been well studied. PspK has been shown to play a role in mouse colonization. We therefore examined PspK-mediated immune evasion along with adherence to host cells and colonization. PspK bound human secretory immunoglobulin A (sIgA) but not the complement regulator factor H and did not decrease C3b deposition on the pneumococcal surface. PspK increased binding of pneumococci to epithelial cells and enhanced pneumococcal colonization independently of the genetic background. Understanding how NTSp colonizes and survives within the nasopharynx is important due to the increase in NTSp carriage. Our data suggest that PspK may aid in the persistence of NTSp within the nasopharynx but is not involved in invasion.

scholarly journals Alternative pathway regulation by factor H modulates Streptococcus pneumoniae induced proinflammatory cytokine responses by decreasing C5a receptor crosstalk

Cytokine ◽  
2016 ◽  
Vol 88 ◽  
pp. 281-286 ◽  
Author(s):  
Erika van der Maten ◽  
Cynthia M. de Bont ◽  
Ronald de Groot ◽  
Marien I. de Jonge ◽  
Jeroen D. Langereis ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Proinflammatory Cytokine ◽  
Alternative Pathway ◽  
Factor H ◽  
C5a Receptor ◽  
Cytokine Responses ◽  
Receptor Crosstalk ◽  
Pathway Regulation

scholarly journals Streptococcus pneumoniae Capsular Serotype Invasiveness Correlates with the Degree of Factor H Binding and Opsonization with C3b/iC3b

2012 ◽  
Vol 81 (1) ◽  
pp. 354-363 ◽  
Author(s):  
Catherine Hyams ◽  
Krzysztof Trzcinski ◽  
Emilie Camberlein ◽  
Daniel M. Weinberger ◽  
Suneeta Chimalapati ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Alternative Pathway ◽  
Principal Component ◽  
Factor H ◽  
Invasive Infection ◽  
Complement Factor ◽  
Invasive Potential ◽  
Content Type ◽  
Complement Resistance ◽  
Mutant Strains

Different capsular serotypes ofStreptococcus pneumoniaevary markedly in their ability to cause invasive infection, but the reasons why are not known. As immunity toS. pneumoniaeinfection is highly complement dependent, variations in sensitivity to complement betweenS. pneumoniaecapsular serotypes could affect invasiveness. We have used 20 capsule-switched variants of strain TIGR4 to investigate whether differences in the binding of the alternative pathway inhibitor factor H (FH) could be one mechanism causing variations in complement resistance and invasive potential between capsular serotypes. Flow cytometry assays were used to assess complement factor binding and complement-dependent neutrophil association for the TIGR4 capsule-switched strains. FH binding varied with the serotype and inversely correlated with the results of factor B binding, C3b/iC3b deposition, and neutrophil association. Differences between strains in FH binding were lost when assays were repeated withpspCmutant strains, and loss of PspC also reduced differences in C3b/iC3b deposition between strains. Median FH binding was high in capsule-switched mutant strains expressing more invasive serotypes, and a principal component analysis demonstrated a strong correlation between serotype invasiveness, high FH binding, and resistance to complement and neutrophil association. Further data obtained with 33 clinical strains also demonstrated that FH binding negatively correlated with C3b/iC3b deposition and that median FH binding was high in strains expressing more invasive serotypes. These data suggest that variations in complement resistance betweenS. pneumoniaestrains and the association of a serotype with invasiveness could be related to capsular serotype effects on FH binding.

scholarly journals Immunogenicity of Streptococcus pneumoniae 74 kDa Surface Protein in Rabbit Model

2016 ◽  
pp. 25-28
Author(s):  
Zeenat Jahan ◽  
Iztiba Mallik Deeba ◽  
Shahina Akter ◽  
Tasmina Rahman ◽  
Ashikun Nabi ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Extraction Procedure ◽  
Rabbit Model ◽  
Surface Protein ◽  
Immunoblot Analysis ◽  
High Titre ◽  
Control Group ◽  
Nitrocellulose Membrane ◽  
Immunoblot Assay ◽  
High Titre Antibody

Immunogenicity of a pneumococcal 74 kDa surface protein in the rabbit model was investigated in this study. For this, Streptococcus pneumoniae serotype 7F was collected and water extraction procedure was applied for the preparation of surface materials, which was used for further isolation of the 74 kDa surface protein. Rabbits were immunized with the sonicated nitrocellulose membrane containing the 74 kDa surface protein and the control group of rabbits was injected with same concentration of sonicated nitrocellulose membrane only. The antibody response against the 74 kDa surface protein was evaluated by both ELISA and immunoblot assay. Sera collected from the 74 kDa surface protein immunized rabbits were examined and the high titre (1:1600) ELISA values (OD490) indicated the production of adequate amounts of anti-74 kDa antibodies in the rabbits. In the immunoblot analysis, a single antigenic band was obtained on the nitrocellulose membrane treated with sera obtained from rabbits immunized with the 74 kDa surface protein. The high titre antibody production in the rabbits indicates the immunogenicity of the 74 kDa surface protein in rabbit model.Bangladesh J Microbiol, Volume 31, Number 1-2,June-Dec 2014, pp 25-28

The common C3F/S polymorphism, R102G, alters factor H regulation of the alternative pathway convertase and combines with other complement variants to influence complement activity in plasma

2010 ◽  
Vol 47 (13) ◽  
pp. 2257-2257
Author(s):  
Meike Heurich ◽  
Ruben Martínez-Barricarte ◽  
Nigel J. Francis ◽  
Dawn L. Roberts ◽  
Santiago Rodríguez de Córdoba ◽  
...  
Keyword(s):  
Alternative Pathway ◽  
Factor H ◽  
Complement Activity ◽  
The Common

scholarly journals Pneumococcal Surface Protein A Inhibits Complement Activation by Streptococcus pneumoniae

1999 ◽  
Vol 67 (9) ◽  
pp. 4720-4724 ◽  
Author(s):  
Anh-Hue T. Tu ◽  
Robert L. Fulgham ◽  
Mark A. McCrory ◽  
David E. Briles ◽  
Alexander J. Szalai
Keyword(s):  
Streptococcus Pneumoniae ◽  
Defense Mechanisms ◽  
Alternative Pathway ◽  
Protein A ◽  
Surface Protein ◽  
Serum Complement ◽  
Factor B ◽  
Pneumococcal Surface Protein A

ABSTRACT Pneumococcal surface protein A (PspA) is a surface-exposed protein virulence factor for Streptococcus pneumoniae. In this study, no significant depletion of serum complement was observed for the serum of mice infected with pneumococci that express PspA. In contrast, in mice infected with an isogenic strain of pneumococci lacking PspA, significant activation of serum complement was detected within 30 min after infection. Also, the PspA-deficient strain but not the PspA-expressing strain was cleared from the blood within 6 h. The contribution of PspA to pneumococcal virulence was further investigated by using mice deficient for C5, C3, or factor B. In mice deficient for C3 or factor B, PspA-negative pneumococci became fully virulent. In contrast, in C5-deficient mice as in wild-type mice, PspA-deficient pneumococci were avirulent. These in vivo data suggest that, in nonimmune mice infected with pneumococci, PspA interferes with complement-dependent host defense mechanisms mediated by factor B. Immunoblots of pneumococci opsonized in vitro suggested that more C3b was deposited on PspA-negative than on PspA-positive pneumococci. This was observed with and without anticapsular antibody. Furthermore, processing of the α chain of C3b was reduced in the presence of PspA. We propose that PspA exerts its virulence function by interfering with deposition of C3b onto pneumococci and/or by inhibiting formation of a fully functional alternative pathway C3 convertase. By blocking recruitment of the alternative pathway, PspA reduces the amount of C3b deposited onto pneumococci, thereby reducing the effectiveness of complement receptor-mediated pathways of clearance.

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