Epitopes on the peplomer protein of infectious bronchitis virus strain M41 as defined by monoclonal antibodies
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H G Niesters1, N M Bleumink-Pluym, A D Osterhaus
1Institute of Virology, Veterinary Faculty, State University, Utrecht, The Netherlands.
Abstract:
Sixteen monoclonal antibodies (Mcabs) were prepared against infectious bronchitis virus strain M41, all of them reacting with the peplomer protein. One of them, Mcab 13, was able to neutralize the virus and to inhibit hemagglutination. Competition binding assays allowed the definition of five epitopes, designated as A, B, C, D, and E, of which epitopes A and B are overlapping. Furthermore, the binding of Mcab 13 (epitope E) could be enhanced by the addition of Mcabs from group B, C, and D. A dot immunoblot assay was used to analyze the effect of denaturation on antibody recognition of the epitopes. Only the binding of Mcab 13 was affected, indicating that the epitope involved in neutralization and hemagglutination is conformation dependent. The epitopes A to D were highly conserved among IBV strains, while epitope E was specific for strains M41 and D3896. In this last strain, however, this epitope was not involved in neutralization.
Insights
Monoclonal antibodies targeting infectious bronchitis virus (IBV) peplomer protein identified five epitopes. One antibody, Mcab 13, neutralizes IBV and recognizes a conformation-dependent epitope.
Area of Science:
- Virology
- Immunology
- Protein Chemistry
Background:
- Infectious bronchitis virus (IBV) is a significant pathogen in poultry.
- The peplomer protein is a key target for neutralizing antibodies.
- Understanding viral epitopes is crucial for vaccine development and diagnostics.
Purpose of the Study:
- To characterize monoclonal antibodies against IBV strain M41 peplomer protein.
- To identify and map epitopes on the IBV peplomer protein.
- To investigate the role of specific epitopes in viral neutralization and hemagglutination.
Main Methods:
- Production and characterization of sixteen monoclonal antibodies (Mcabs) against IBV M41.
- Virus neutralization and hemagglutination inhibition assays.
- Competition binding assays and dot immunoblot assays to analyze epitope interactions and conformation dependence.
Main Results:
- All Mcabs reacted with the peplomer protein; Mcab 13 neutralized the virus and inhibited hemagglutination.
- Five distinct epitopes (A-E) were defined, with A and B overlapping.
- Epitope E, recognized by Mcab 13, is conformation-dependent and specific to certain IBV strains, influencing neutralization.
Conclusions:
- Monoclonal antibody mapping revealed conserved and strain-specific epitopes on the IBV peplomer.
- The conformation-dependent nature of epitope E is critical for its role in viral neutralization.
- These findings contribute to understanding IBV immunopathogenesis and epitope-based vaccine strategies.