scholarly journals Relationship between Surface Accessibility for PpmA, PsaA, and PspA and Antibody-Mediated Immunity to Systemic Infection by Streptococcus pneumoniae

2005 ◽  
Vol 73 (3) ◽  
pp. 1304-1312 ◽  
Author(s):  
Dennis O. Gor ◽  
Xuedong Ding ◽  
David E. Briles ◽  
Michael R. Jacobs ◽  
Neil S. Greenspan
Keyword(s):  
Streptococcus Pneumoniae ◽  
Capsular Polysaccharide ◽  
Protein A ◽  
Age Groups ◽  
Pneumococcal Infection ◽  
Systemic Infection ◽  
Surface Protein ◽  
Target Antigen ◽  
Age Related ◽  
Type 3

ABSTRACT Antibodies to capsular polysaccharide (PS) are protective against systemic infection by Streptococcus pneumoniae, but the large number of pneumococcal serogroups and the age-related immunogenicity of pure PS limit the utility of PS-based vaccines. In contrast, cell wall-associated proteins from different capsular serotypes can be cross-reactive and immunogenic in all age groups. Therefore, we evaluated three pneumococcal proteins with respect to relative accessibility to antibody, in the context of intact pneumococci, and their ability to elicit protection against systemic infection by encapsulated S. pneumoniae. Sequences encoding pneumococcal surface adhesin A (PsaA), putative protease maturation protein A (PpmA), and the N-terminal region of pneumococcal surface protein A (PspA) from S. pneumoniae strain A66.1 were cloned and expressed in Escherichia coli. The presence of genes encoding PsaA, PpmA, and PspA in 11 clinical isolates was examined by PCR, and the expression of these proteins by each strain was examined by Western blotting with antisera raised to the respective recombinant proteins. We used flow cytometry to demonstrate that PspA was readily detectable on the surface of the pneumococcal strains analyzed, whereas PsaA and PpmA were not. Consistent with these observations, mice with passively or actively acquired antibodies to PspA or type 3 PS were equivalently protected from homologous systemic challenge with type 3 pneumococci, whereas mice with passively or actively acquired antibodies to PsaA or PpmA were not effectively protected. These experiments support the hypothesis that the extent of protection against systemic pneumococcal infection is influenced by target antigen accessibility to circulating host antibodies.

scholarly journals Conjugation of PspA4Pro with Capsular Streptococcus pneumoniae Polysaccharide Serotype 14 Does Not Reduce the Induction of Cross-Reactive Antibodies

2017 ◽  
Vol 24 (8) ◽  
Author(s):  
Míriam A. da Silva ◽  
Thiago R. Converso ◽  
Viviane M. Gonçalves ◽  
Luciana C. C. Leite ◽  
Martha M. Tanizaki ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Capsular Polysaccharide ◽  
Vaccine Coverage ◽  
Protein A ◽  
Surface Protein ◽  
Cross Reactivity ◽  
Carrier Protein ◽  
Content Type ◽  
Clade 1 ◽  
The Impact

ABSTRACT Current pneumococcal vaccines are composed of bacterial polysaccharides as antigens, plain or conjugated to carrier proteins. While efficacious against vaccine serotypes, epidemiologic data show an increasing incidence of infections caused by nonvaccine serotypes of Streptococcus pneumoniae. The use of pneumococcal surface protein A (PspA) as a carrier protein in a conjugate vaccine could help prevent serotype replacement by increasing vaccine coverage and reducing selective pressure of S. pneumoniae serotypes. PspA is present in all pneumococcal strains, is highly immunogenic, and is known to induce protective antibodies. Based on its sequence, PspA has been classified into three families and six clades. A PspA fragment derived from family 2, clade 4 (PspA4Pro), was shown to generate antibodies with a broad range of cross-reactivity, across clades and families. Here, PspA4Pro was modified and conjugated to capsular polysaccharide serotype 14 (PS14). We investigated the impact of conjugation on the immune response induced to PspA4Pro and PS14. Mice immunized with the PS14-mPspA4Pro conjugate produced higher titers of anti-PS14 antibodies than the animals that received coadministered antigens. The conjugate induced antibodies with opsonophagocytic activity against PS14-carrying strains, as well as against a panel of strains bearing PspAs from five clades (encompassing families 1 and 2) bearing a non-PS14 serotype. Furthermore, mice immunized with PS14-mPspA4Pro were protected against nasal colonization with a nonrelated S. pneumoniae strain bearing PspA from clade 1, serotype 6B. These results demonstrate that the cross-reactivity mediated by PspA4Pro is retained following conjugation, supporting the use of PspA4 as a carrier protein in order to enhance pneumococcal vaccine coverage and encourage its further investigation as a candidate in future vaccine designs.

scholarly journals Relative Roles of Genetic Background and Variation in PspA in the Ability of Antibodies to PspA To Protect against Capsular Type 3 and 4 Strains of Streptococcus pneumoniae

2003 ◽  
Vol 71 (8) ◽  
pp. 4498-4505 ◽  
Author(s):  
Hazeline Roche ◽  
Bing Ren ◽  
Larry S. McDaniel ◽  
Anders Håkansson ◽  
David E. Briles
Keyword(s):  
Streptococcus Pneumoniae ◽  
Genetic Background ◽  
Protein A ◽  
Surface Protein ◽  
Genetically Engineered ◽  
Capsular Type ◽  
Single Family ◽  
Fatal Infection ◽  
Human Use ◽  
Type 3

ABSTRACT Pneumococcal surface protein A (PspA) is able to elicit antibodies in mice and humans that can protect mice against fatal infection with Streptococcus pneumoniae. It has been observed that immunization with a single family 1 PspA can protect mice against infections with capsular type 3 or 6B strains expressing PspA family 1 or 2. However, several studies have shown that immunity to PspA is less efficacious against several capsular type 4 strains than against strains of capsular types 3, 6A, and 6B. To determine whether the greater difficulty in protecting against capsular type 4 strains resulted from differences in their PspAs or from differences in their genetic backgrounds, we performed protection experiments using four different challenge strains: a capsular type 3 strain expressing a family 1 PspA (WU2), a capsular type 4 strain expressing a family 2 PspA (TIGR4), and genetically engineered variants of WU2 and TIGR4 expressing each other's PspAs. Prior to infection, the mice were immunized with recombinant family 1 or family 2 PspA. The results revealed that much of the difficulty in protecting against capsular type 4 strains was eliminated when mice were immunized with a homologous PspA of the same PspA family. However, regardless of which PspA the strains expressed, those on the TIGR4 background were about twice as hard to protect against as WU2 strains expressing the same PspA based on the efficacy rates seen in our experiments. These results point out the importance of including more than one PspA in any PspA vaccines developed for human use.

scholarly journals Genetic Alteration of Capsule Type but Not PspA Type Affects Accessibility of Surface-Bound Complement and Surface Antigens of Streptococcus pneumoniae

2003 ◽  
Vol 71 (1) ◽  
pp. 218-225 ◽  
Author(s):  
Melanie Abeyta ◽  
Gail G. Hardy ◽  
Janet Yother
Keyword(s):  
Streptococcus Pneumoniae ◽  
Immune Responses ◽  
Protein A ◽  
Surface Protein ◽  
Surface Antigens ◽  
Capsular Polysaccharides ◽  
Capsule Type ◽  
Type 3 ◽  
Determining Factor

ABSTRACT The Streptococcus pneumoniae capsular polysaccharides and pneumococcal surface protein A (PspA) are major determinants of virulence that are antigenically variable and capable of eliciting protective immune responses. By genetically switching the pspA genes of the capsule type 2 strain D39 and the capsule type 3 strain WU2, we showed that the different abilities of antibody to PspA to protect against these strains was not related to the PspA type expressed. Similarly, the level of specific antibody binding to PspA, other surface antigens, and surface-localized C3b did not depend on the PspA type but instead was correlated with the capsule type. The type 3 strain WU2 and an isogenic derivative of D39 that expresses the type 3 capsule bound nearly identical amounts of antibody to PspA and other surface antigens, and these amounts were less than one-half the amount observed with the type 2 parent strain D39. Expression of the type 3 capsule in D39 also reduced the amount of C3b deposited and its accessibility to antibody, resulting in a level intermediate between the levels observed with WU2 and D39. Despite these effects, the capsule type was not the determining factor in anti-PspA-mediated protection, as both D39 and its derivative expressing the type 3 capsule were more resistant to protection than WU2. The specific combination of PspA and capsule type also did not determine the level of protection. The capsule structure is thus a major determinant in accessibility of surface antigens to antibody, but certain strains appear to express other factors that can influence antibody-mediated protection.

scholarly journals Modified Opsonization, Phagocytosis, and Killing Assays To Measure Potentially Protective Antibodies against Pneumococcal Surface Protein A

2013 ◽  
Vol 20 (10) ◽  
pp. 1549-1558 ◽  
Author(s):  
Calvin C. Daniels ◽  
Kyung-Hyo Kim ◽  
Robert L. Burton ◽  
Shaper Mirza ◽  
Melissa Walker ◽  
...  
Keyword(s):  
Capsular Polysaccharide ◽  
Protein A ◽  
Surface Protein ◽  
Pneumococcal Surface Protein A ◽  
Target Strain ◽  
Human Sera ◽  
Protective Antibodies ◽  
Normal Human ◽  
Type 3

ABSTRACTThe standard opsonophagocytosis killing assay (OPKA) for antibodies to pneumococcal capsular polysaccharide was modified to permit an evaluation of the protection-mediating antibodies to pneumococcal surface protein A (PspA). We found that by increasing the incubation time with the complement and phagocytes from 45 min to 75 min, the protective activity was readily detected. In another modification, we used a capsule type 2 target strain that expressed PspA but not pneumococcal surface protein C (PspC). With these modifications separately or in combination, rabbit antisera to the recombinant α-helical or proline-rich domains of PspA mediated >50% killing of the target strain. The ability of normal human sera to mediate the killing of pneumococci in this modified OPKA correlated with their levels of antibodies to PspA and their ability to protect mice against fatal infection with a type 3 strain. Passive protection of mice against pneumococci and killing in the modified OPKA were lost when normal human sera were adsorbed with recombinant PspA (rPspA) on Sepharose, thus supporting the potential utility of the modified OPKA to detect protective antibodies to PspA. In the standard OPKA, monoclonal antibodies to PspA were strongly protective in the presence of subprotective amounts of anti-capsule. Thus, the currently established high-throughput OPKA for antibodies to capsule could be modified in one of two ways to permit an evaluation of the opsonic efficacy of antibodies to PspA.

scholarly journals PspA Family Fusion Proteins Delivered by Attenuated Salmonella enterica Serovar Typhimurium Extend and Enhance Protection against Streptococcus pneumoniae

2009 ◽  
Vol 77 (10) ◽  
pp. 4518-4528 ◽  
Author(s):  
Wei Xin ◽  
Yuhua Li ◽  
Hua Mo ◽  
Kenneth L. Roland ◽  
Roy Curtiss
Keyword(s):  
Streptococcus Pneumoniae ◽  
Fusion Protein ◽  
Fusion Proteins ◽  
Protein A ◽  
Pneumococcal Infection ◽  
Surface Protein ◽  
Oral Immunization ◽  
Secretion Signal ◽  
Multiple Strains ◽  
Strain Family

ABSTRACTPneumococcal surface protein A (PspA) is highly immunogenic and can induce a protective immune response against pneumococcal infection. PspA is divided into two major families based on serological variability: family 1 and family 2. To provide broad protection, PspA proteins from pneumococcal strains Rx1 (family 1) and EF5668 (family 2) were combined to form two PspA fusion proteins, PspA/Rx1-EF5668 and PspA/EF5668-Rx1. Each protein was fused to a type II secretion signal and delivered by a recombinant attenuatedSalmonellavaccine (RASV). Both PspA/Rx1-EF5668 and PspA/EF5668-Rx1 were synthesized in the RASV and secreted into the periplasm and supernatant. The fusion proteins reacted strongly with both anti-PspA/Rx1 and anti-PspA/EF5668 antisera. Oral immunization of BALB/c mice with RASV synthesizing either PspA fusion protein elicited serum immunoglobulin G (IgG) and mucosal IgA responses against both families of PspA. Analysis of IgG isotypes (IgG2a and IgG1) indicated a strong Th1 bias to the immune responses to both proteins. Sera from mice immunized with RASV synthesizing PspA/Rx1-EF5668 bound to the surface and directed C3 complement deposition on representative strains from all five PspA clades. Immunization with RASV synthesizing either protein protected mice against intraperitoneal challenge withStreptococcus pneumoniaeWU2 strain (family 1), intravenous challenge withS. pneumoniae3JYP2670 strain (family 2), and intranasal challenge withS. pneumoniaeA66.1 (family 1). The PspA/Rx1-EF5668 protein elicited significantly greater protection than PspA/EF5668-Rx1, PspA/Rx1, or PspA/EF5668. These results indicate an RASV synthesizing a PspA fusion protein representing both PspA families constitutes an effective antipneumococcal vaccine, extending and enhancing protection against multiple strains ofS. pneumoniae.

scholarly journals Conjugation of Polysaccharide 6B from Streptococcus pneumoniae with Pneumococcal Surface Protein A: PspA Conformation and Its Effect on the Immune Response

2013 ◽  
Vol 20 (6) ◽  
pp. 858-866 ◽  
Author(s):  
Catia T. Perciani ◽  
Giovana C. Barazzone ◽  
Cibelly Goulart ◽  
Eneas Carvalho ◽  
Joaquin Cabrera-Crespo ◽  
...  
Keyword(s):  
Immune Response ◽  
Streptococcus Pneumoniae ◽  
Conjugate Vaccine ◽  
Reductive Amination ◽  
Capsular Polysaccharide ◽  
Protective Antigen ◽  
Protein A ◽  
Surface Protein ◽  
Promising Alternative ◽  
Pneumococcal Surface Protein A

ABSTRACTDespite the substantial beneficial effects of incorporating the 7-valent pneumococcal conjugate vaccine (PCV7) into immunization programs, serotype replacement has been observed after its widespread use. As there are many serotypes currently documented, the use of a conjugate vaccine relying on protective pneumococcal proteins as active carriers is a promising alternative to expand PCV coverage. In this study, capsular polysaccharide serotype 6B (PS6B) and recombinant pneumococcal surface protein A (rPspA), a well-known protective antigen fromStreptococcus pneumoniae, were covalently attached by two conjugation methods. The conjugation methodology developed by our laboratory, employing 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM) as an activating agent through carboxamide formation, was compared with reductive amination, a classical methodology. DMT-MM-mediated conjugation was shown to be more efficient in coupling PS6B to rPspA clade 1 (rPspA1): 55.0% of PS6B was in the conjugate fraction, whereas 24% was observed in the conjugate fraction with reductive amination. The influence of the conjugation process on the rPspA1 structure was assessed by circular dichroism. According to our results, both conjugation processes reduced the alpha-helical content of rPspA; reduction was more pronounced when the reaction between the polysaccharide capsule and rPspA1 was promoted between the carboxyl groups than the amine groups (46% and 13%, respectively). Regarding the immune response, both conjugates induced functional anti-rPspA1 and anti-PS6B antibodies. These results suggest that the secondary structure of PspA1, as well as its reactive groups (amine or carboxyl) involved in the linkage to PS6B, may not play an important role in eliciting a protective immune response to the antigens.

scholarly journals Acquired, but Not Innate, Immune Responses to Streptococcus pneumoniae Are Compromised by Neutralization of CD40L

2000 ◽  
Vol 68 (2) ◽  
pp. 511-517 ◽  
Author(s):  
Young-il Hwang ◽  
Moon H. Nahm ◽  
David E. Briles ◽  
David Thomas ◽  
Jeffrey M. Purkerson
Keyword(s):  
Streptococcus Pneumoniae ◽  
Capsular Polysaccharide ◽  
Pneumococcal Infection ◽  
Systemic Infection ◽  
Humoral Response ◽  
Nasal Carriage ◽  
The Elderly ◽  
Antibody Responses ◽  
Capsular Polysaccharides ◽  
Cell Wall Polysaccharides

ABSTRACT Streptococcus pneumoniae is a significant pathogen of young children and the elderly. Systemic infection by pneumococci is a complex process involving several bacterial and host factors. We have investigated the role of CD40L in host defense against pneumococcal infection. Treatment of mice with MR-1 antibody (anti-CD154/CD40L) markedly reduced antibody responses to the pneumococcal protein PspA, elicited by immunization of purified protein or whole bacteria. In mice immunized with whole bacteria, MR-1 treatment reduced antibody responses to capsular polysaccharides but not cell wall polysaccharides. MR-1 did not suppress antibody responses to isolated capsular polysaccharides but did reduce the production of antibody to a capsular polysaccharide-protein conjugate, indicating that when presented in the context of whole bacteria, the humoral response to capsular polysaccharides is partially T-cell dependent. Despite the reduction of the protective humoral responses to pneumococcal infection, administration of MR-1 had no effect on sepsis, lung infection, or nasal carriage in nonimmune mice inoculated with virulent pneumococci. Thus, short-term neutralization of CD40L does not compromise innate host defenses against pneumococcal invasion.

Protection induced by pneumococcal surface protein A (PspA) is enhanced by conjugation to a Streptococcus pneumoniae capsular polysaccharide

Vaccine ◽  
2008 ◽  
Vol 26 (23) ◽  
pp. 2925-2929 ◽  
Author(s):  
Fátima C.L. Csordas ◽  
Cátia T. Perciani ◽  
Michelle Darrieux ◽  
Viviane M. Gonçalves ◽  
Joaquim Cabrera-Crespo ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Capsular Polysaccharide ◽  
Protein A ◽  
Surface Protein ◽  
Pneumococcal Surface Protein A

scholarly journals Dendritic Cell-Derived Exosomes Express a Streptococcus pneumoniae Capsular Polysaccharide Type 14 Cross-Reactive Antigen That Induces Protective Immunoglobulin Responses against Pneumococcal Infection in Mice

2006 ◽  
Vol 75 (1) ◽  
pp. 220-230 ◽  
Author(s):  
Jesus Colino ◽  
Clifford M. Snapper
Keyword(s):  
Streptococcus Pneumoniae ◽  
Dendritic Cell ◽  
Capsular Polysaccharide ◽  
Pneumococcal Infection ◽  
Natural Immunity ◽  
Lethal Challenge ◽  
Humoral Immune ◽  
Humoral Immune Responses ◽  
Type 3

ABSTRACT Exosomes activate T cells in vivo, but whether exosomes are able to induce humoral immune responses is still unknown. We found that dendritic cells, but not other immune cells, constitutively release an exosome-associated glycoconjugate that is cross-reactive with the capsular polysaccharide of Streptococcus pneumoniae type 14 (Cps14-CRA). Cps14-CRA was localized to the cholesterol-enriched microdomains or rafts of the exosomes and was mapped to the β1→6 branched N-acetyl-lactosamine derivatives of the Cps14-CRA. Injection of CFA-primed naive mice with purified dendritic cell exosomes induced immunoglobulin (Ig) anti-Cps14 responses composed predominantly of IgM, IgG3, and IgG1. These responses were associated with protection against a lethal challenge with live S. pneumoniae type 14, but not with type 3 bacteria, and was correlated with the titer of elicited IgM and IgG3 anti-Cps14. These data show, for the first time, that exosomes can induce a humoral immune response to an associated unprocessed, autologous antigen. Although anti-Cps14 Ig responses are specifically demonstrated, these could reflect a broader mechanism that modulates both natural immunity and autoimmunity to other glycotopes.

scholarly journals Pneumococcal Diversity: Considerations for New Vaccine Strategies with Emphasis on Pneumococcal Surface Protein A (PspA)

1998 ◽  
Vol 11 (4) ◽  
pp. 645-657 ◽  
Author(s):  
David E. Briles ◽  
Rebecca Creech Tart ◽  
Edwin Swiatlo ◽  
Joseph P. Dillard ◽  
Patricia Smith ◽  
...  
Keyword(s):  
Capsular Polysaccharide ◽  
Protein A ◽  
Pneumococcal Infection ◽  
Significant Risk ◽  
Surface Protein ◽  
Infectious Agent ◽  
The Elderly ◽  
Multidrug Resistant ◽  
Pneumococcal Surface Protein A ◽  
Potential Vaccine

SUMMARY Streptococcus pneumoniae is a problematic infectious agent, whose seriousness to human health has been underscored by the recent rise in the frequency of isolation of multidrug-resistant strains. Pneumococcal pneumonia in the elderly is common and often fatal. Young children in the developing world are at significant risk for fatal pneumococcal respiratory disease, while in the developed world otitis media in children results in substantial economic costs. Immunocompromised patients are extremely susceptible to pneumococcal infection. With 90 different capsular types thus far described, the diversity of pneumococci contributes to the challenges of preventing and treating S. pneumoniae infections. The current capsular polysaccharide vaccine is not recommended for use in children younger than 2 years and is not fully effective in the elderly. Therefore, innovative vaccine strategies to protect against this agent are needed. Given the immunogenic nature of S. pneumoniae proteins, these molecules are being investigated as potential vaccine candidates. Pneumococcal surface protein A (PspA) has been evaluated for its ability to elicit protection against S. pneumoniae infection in mouse models of systemic and local disease. This review focuses on immune system responsiveness to PspA and the ability of PspA to elicit cross-protection against heterologous strains. These parameters will be critical to the design of broadly protective pneumococcal vaccines.

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