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Characterization of Thymus-dependent and Thymus-independent Immunoglobulin Isotype Responses in Mice Using Enzyme-linked Immunosorbent Assay
Published on: September 7, 2018
Antibody classes & subclasses induced by mucosal immunization of mice with Streptococcus pyogenes M6 protein &
R Teloni1, C von Hunolstein, S Mariotti
1Istituto Superiore di Sanità, Rome, Italy.
Background & Objectives:
Type-specific antibodies against M protein are critical for human protection as they enhance phagocytosis and are protective. An ideal vaccine for the protection against Streptococcus pyogenes would warrant mucosal immunity, but mucosally administered M-protein has been shown to be poorly immunogenic in animals. We used a recombinant M type 6 protein to immunize mice in the presence of synthetic oligodeoxynucleotides containing CpG motifs (immunostimulatory sequences: ISS) or cholera toxin (CT) to explore its possible usage in a mucosal vaccine.
Methods:
Mice were immunized by intranasal (in) or intradermal (id) administration with four doses at weekly intervals of M6-protein (10 microg/mouse) with or without adjuvant (ISS, 10 microg/mouse or CT, 0,5 microg/mouse). M6 specific antibodies were measured by enzyme linked immunosorbent assay using class and subclass specific monoclonal antibodies.
Results:
The use of ISS induced an impressive anti M-protein serum IgG response but when id administered was not detectable in the absence of adjuvant. When used in, M-protein in the presence of both ISS and CT induced anti M-protein IgA in the bronchoalveolar lavage, as well as specific IgG in the serum. IgG were able to react with serotype M6 strains of S. pyogenes. The level of antibodies obtained by immunizing mice in with M-protein and CT was higher in comparison to M-protein and ISS. The analysis of anti-M protein specific IgG subclasses showed high levels of IgG1, IgG2a and IgG2b, and low levels of IgG3 when ISS were used as adjuvant. Thus, in the presence of ISS, the ratio IgG2a/IgG1 and (IgG2a+IgG3)/IgG1 >1 indicated a type 1-like response obtained both in mucosally or systemically vaccinated mice.
Interpretation & Conclusion:
Our study offers a reproducible model of anti-M protein vaccination that could be applied to test new antigenic formulations to induce an anti-group A Streptococcus (GAS) vaccination suitable for protection against the different diseases caused by this bacterium.
Insights
This study explored using M protein with adjuvants for a Streptococcus pyogenes vaccine. Intranasal administration with CpG motifs or cholera toxin successfully generated protective antibodies.
Area of Science:
- Immunology
- Vaccinology
- Microbiology
Background:
- Type-specific antibodies against M protein are crucial for protection against Streptococcus pyogenes.
- Mucosal immunity is ideal for vaccines, but M-protein is poorly immunogenic when administered mucosally.
- Recombinant M type 6 protein was used to explore its potential in a mucosal vaccine.
Purpose of the Study:
- To evaluate the immunogenicity of recombinant M type 6 protein with adjuvants (ISS or CT) for potential mucosal vaccination against Streptococcus pyogenes.
- To investigate the induction of specific antibodies (IgG and IgA) in serum and mucosal secretions.
- To assess the type of immune response generated.
Main Methods:
- Mice were intranasally or intradermally immunized with M6-protein and adjuvants (ISS or CT).
- Antibody responses were measured using enzyme-linked immunosorbent assay (ELISA).
- Specific IgG subclasses were analyzed to determine the immune response profile.
Main Results:
- Intranasal administration of M-protein with ISS or CT induced anti-M-protein IgA in bronchoalveolar lavage and serum IgG.
- Cholera toxin (CT) as an adjuvant resulted in higher antibody levels compared to ISS when administered intranasally.
- ISS induced a type 1-like immune response, indicated by IgG subclass ratios.
Conclusions:
- A reproducible model for anti-M protein vaccination was established.
- This model can be used to test new vaccine formulations for protection against Streptococcus pyogenes.
- The findings support the development of effective anti-group A Streptococcus (GAS) vaccines.
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