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Peptides that mimic the group B streptococcal type III capsular polysaccharide antigen
S H Pincus1, M J Smith, H J Jennings
1Department of Microbiology, Montana State University, Bozeman 59717-3520, USA. spincus@montana.edu
Journal of Immunology (Baltimore, Md. : 1950)
|April 29, 1998
Summary
Researchers developed a peptide mimetic that elicits antibodies against the type III group B streptococcus (GBS) capsular polysaccharide, a poor immunogen. This peptide approach may improve vaccine efficacy for carbohydrate epitopes.
Area of Science:
- Immunology
- Microbiology
- Vaccine Development
Background:
- Microbial polysaccharides are generally poor immunogens, limiting antibody production against critical carbohydrate epitopes.
- Developing effective vaccines against encapsulated bacteria like group B Streptococcus (GBS) is challenging due to the poor immunogenicity of their capsular polysaccharides.
Purpose of the Study:
- To develop an alternative method for generating antibodies against carbohydrate epitopes, specifically targeting the type III capsular polysaccharide of GBS.
- To identify and characterize peptide analogues that mimic the GBS type III capsular polysaccharide epitope.
Main Methods:
- Utilized a protective monoclonal antibody (mAb) S9 against GBS type III polysaccharide to select epitope analogues from a peptide display phage library.
- Employed ELISA to confirm phage binding to mAb S9 and assessed inhibition of S9-GBS binding by selected peptides.
- Synthesized a peptide analogue (FDTGAFDPDWPA) and conjugated it to carriers for immunization in mice.
Main Results:
- Two phage populations displaying peptide sequences (WENWMMGNA and FDTGAFDPDWPA) were identified that bound specifically to mAb S9.
- The peptide FDTGAFDPDWPA effectively inhibited the binding of mAb S9 to GBS type III polysaccharide.
- Immunization of mice with the peptide conjugate elicited significant antibody responses against GBS and its capsular polysaccharide.
Conclusions:
- A peptide mimetic of the GBS type III capsular polysaccharide has been successfully developed, demonstrating both antigenicity and immunogenicity.
- This peptide-based approach can induce protective antibodies against poorly immunogenic carbohydrate antigens.
- Incorporating such peptide mimetics into vaccines holds promise for enhancing immune responses to bacterial carbohydrate epitopes.