Specificity and Protective Activity of Murine Monoclonal Antibodies Directed Against the Capsular Polysaccharide of Type III Group B Streptococci

Hybridoma ◽  
1992 ◽  
Vol 11 (1) ◽  
pp. 13-22 ◽  
Author(s):  
G. TETI ◽  
M. CALAPAI ◽  
G. CALOGERO ◽  
F. TOMASELLO ◽  
G. MANCUSO ◽  
...  



1999 ◽  
Vol 67 (5) ◽  
pp. 2491-2496 ◽  
Author(s):  
Claudia Gravekamp ◽  
Dennis L. Kasper ◽  
Lawrence C. Paoletti ◽  
Lawrence C. Madoff

ABSTRACT The alpha C protein, a protective surface protein of group B streptococci (GBS), is present in most non-type III GBS strains. Conjugate vaccines composed of the alpha C protein and type III capsular polysaccharide (CPS) might be protective against most GBS infections. In this study, the type III CPS was covalently coupled to full-length, nine-repeat alpha C protein (resulting in III-α9r conjugate vaccine) or to two-repeat alpha C protein (resulting in III-α2r conjugate vaccine) by reductive amination. Initial experiments with the III-α9r vaccine showed that it was poorly immunogenic in mice with respect to both vaccine antigens and was suboptimally efficacious in providing protection in mice against challenge with GBS. Therefore, modified vaccination protocols were used with the III-α2r vaccine. Female mice were immunized three times with 0.5, 5, or 20 μg of the III-α2r vaccine with an aluminum hydroxide adjuvant and bred. Ninety-five percent of neonatal mice born to dams immunized with the III-α2r vaccine survived challenge with GBS expressing type III CPS, and 60% survived challenge with GBS expressing wild-type (nine-repeat) alpha C protein; 18 and 17%, respectively, of mice in the negative control groups survived (P, <0.0001). These protection levels did not differ significantly from those obtained with the type III CPS-tetanus toxoid conjugate vaccine and the unconjugated two-repeat alpha C protein, which protected 98 and 58% of neonates from infection with GBS expressing type III CPS or the alpha C protein, respectively. Thus, the two-repeat alpha C protein in the vaccine was immunogenic and simultaneously enhanced the immunogenicity of type III CPS. III-α vaccines may be alternatives to GBS polysaccharide-tetanus toxoid vaccines, eliciting additional antibodies protective against GBS infection.





2000 ◽  
Vol 68 (4) ◽  
pp. 2053-2060 ◽  
Author(s):  
Esam A. Albanyan ◽  
Jesus G. Vallejo ◽  
C. Wayne Smith ◽  
Morven S. Edwards

ABSTRACT Nonopsonic interaction of host immune cells with pathogens is an important first line of defense. We hypothesized that nonopsonic recognition between type III group B streptococcus and human neutrophils would occur and that the interaction would be sufficient to trigger neutrophil activation. By using a serum-free system, it was found that heat-killed type III group B streptococci bound to neutrophils in a rapid, stable, and inoculum-dependent manner that did not result in ingestion. Transposon-derived type III strain COH1-13, which lacks capsular polysaccharide, and strain COH1-11 with capsular polysaccharide lacking terminal sialic acid demonstrated increased neutrophil binding, suggesting that capsular polysaccharide masks an underlying binding site. Experiments using monoclonal antibodies to complement receptor 1 and to the I domain or lectin site of complement receptor 3 did not inhibit binding, indicating that the complement receptors used for ingestion of opsonized group B streptococci were not required for nonopsonic binding. Nonopsonic binding resulted in rapid activation of cellular p38 and p44/42 mitogen-activated protein kinases. This interaction was not an effective trigger for superoxide production but did promote release of the proinflammatory cytokine interleukin-8. The release of interleukin-8 was markedly suppressed by the p38 mitogen-activated protein kinase inhibitor SB203580 but was only minimally suppressed by the mitogen-activated protein/extracellular signal-regulated kinase inhibitor PD98059. Thus, nonopsonic binding of type III group B streptococci to neutrophils is sufficient to initiate intracellular signaling pathways and could serve as an arm of innate immunity of particular importance to the immature host.



1983 ◽  
Vol 158 (3) ◽  
pp. 1006-1011 ◽  
Author(s):  
M L Egan ◽  
D G Pritchard ◽  
H C Dillon ◽  
B M Gray

Mouse hybridoma antibodies of several major classes against group B streptococcus type III have been produced. Mice were immunized with either whole heat-killed or acid-treated organisms to obtain antibodies against both the complete (sialated) or incomplete (nonsialated) forms of the type III polysaccharide. Resulting monoclonal antibodies showed exclusive specificity for either the complete or incomplete antigen. The ability of these antibodies to protect mice from a lethal challenge of live type III organisms was tested with a mucin model that permitted use of very small inocula given intraperitoneally with antibody and mucin. Antibodies specific for the nonsialated antigen were not protective, whether of IgM, IgG2a, or IgG3 isotypes. Antibodies specific for the complete antigen were, however, highly protective, including monoclonals of IgM, IgG2a, and IgA isotypes. These mouse monoclonal antibodies against group B streptococci that are directed against either complete or incomplete antigenic determinants, and include isotypes other than IgM, should be particularly useful for studying the mechanism of protection against experimental infection.



2002 ◽  
Vol 70 (11) ◽  
pp. 6409-6415 ◽  
Author(s):  
Qi Cheng ◽  
Steven Debol ◽  
Hong Lam ◽  
Ron Eby ◽  
Lorri Edwards ◽  
...  

ABSTRACT Group B streptococci (GBS) are among the most common causes of life-threatening neonatal infections. Vaccine development since the late 1970s has focused on the capsular polysaccharides, but a safe, effective product is still not available. Our quest for a vaccine turned to the streptococcal C5a peptidase (SCPB). This surface protein is antigenically conserved across most if not all serotypes. A murine model was used to assess the impact of SCPB on clearance of GBS from the lungs of intranasally infected animals. Mutational inactivation of SCPB resulted in more-rapid clearance of streptococci from the lung. Immunization with recombinant SCPB alone or SCPB conjugated to type III capsular polysaccharide produced serotype-independent protection, which was evidenced by more-rapid clearance of the serotype VI strain from the lungs. Immunization of mice with tetanus toxoid-type III polysaccharide conjugate did not produce protection, confirming that protection induced by SCPB conjugates was independent of type III polysaccharide antigen. Histological evaluation of lungs from infected mice revealed that pathology in animals immunized with SCPB or SCPB conjugates was significantly less than that in animals immunized with a tetanus toxoid-polysaccharide conjugate. These experiments suggest that inclusion of C5a peptidase in a vaccine will both add another level to and broaden the spectrum of the protection of a polysaccharide vaccine.



2017 ◽  
Vol 89 (7) ◽  
pp. 855-875 ◽  
Author(s):  
Vittorio Cattaneo ◽  
Filippo Carboni ◽  
Davide Oldrini ◽  
Riccardo De Ricco ◽  
Nunzio Donadio ◽  
...  

AbstractGroup B Streptococcus type III (GBSIII) is the most relevant serotype among GBS strains causing infections and the potential of its capsular polysaccharide conjugated to a protein carrier as vaccine is well documented. Polysaccharide from GBSIII (PSIII) can form helical structures in solution where negatively charged sialic acid residues would be disposed externally providing stabilization to the helix. A peculiar high affinity to specific monoclonal antibodies (mAbs) has been reported for PSIII, and fragments of diverse size bind to mAbs in a length dependent manner. These data have been rationalized in terms of conformational epitopes that would be formed by fragments with >4 saccharidic repeating units. Saturation Transfer Difference NMR experiments have demonstrated that the sialic acid residue is not involved in antibody recognition. However the molecular basis of the interaction between PSIII and mAbs has not been fully elucidated. An important prerequisite to achieve this would be the availability of the three possible sugar sequences representing the pentasaccharide PSIII repeating unit. Herein we established a [2+3] convergent approach leading to these three pentasaccharides (1–3) with the end terminal sugar bearing a linker for possible conjugation. The PSIII fragments were coupled to the genetically detoxified diphtheria toxin CRM197 to prove by ELISA that the three pentasaccharides are recognized by polyclonal anti-PSIII serum. The presence of the branching formed by a Glc residue β-(1→6) linked to GlcNAc was proven an important motif for antibody recognition.



1993 ◽  
Vol 61 (2) ◽  
pp. 478-485 ◽  
Author(s):  
R L Gibson ◽  
M K Lee ◽  
C Soderland ◽  
E Y Chi ◽  
C E Rubens


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