Mapping of a surface-exposed B-cell epitope to the variable sequent 3 of the major outer-membrane protein of Chlamydia trachomatis
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1Department of Pathology, University of California, Irvine 92717-4800.
Abstract:
A B-cell epitope, AEFPLDIT, was located to the variable sequent 3 of the major outer-membrane protein (MOMP) using the monoclonal antibody L3-1, raised to the Chlamydia trachomatis serovar L3 MOMP. By Western blot and inclusion immunofluorescence assay the monoclonal antibody recognized all the C complex and C-related complex serovars of C. trachomatis, except serovar C. Dot-blot and ELISA data using native elementary bodies indicated that the epitope was surface exposed. The monoclonal antibody, at concentrations of 10 and 100 micrograms per 10(7) chlamydial inclusion-forming units, was able to neutralize the infectivity of chlamydia in an in vivo assay but did not neutralize chlamydia in vitro or in a mouse toxicity assay. A peptide corresponding to the variable sequent 3 has previously been shown to also elicit a T-cell response; thus, careful consideration should be given to inclusion of this region of the major outer-membrane protein in a subunit vaccine.
Insights
A specific B-cell epitope on Chlamydia trachomatis was identified. This epitope, located on the major outer-membrane protein, shows potential for a subunit vaccine by neutralizing infectivity in vivo.
Area of Science:
- Immunology
- Microbiology
- Vaccine Development
Background:
- The major outer-membrane protein (MOMP) of Chlamydia trachomatis is a key target for immune responses.
- Understanding B-cell epitopes on MOMP is crucial for developing effective vaccines against chlamydial infections.
Purpose of the Study:
- To identify and characterize a specific B-cell epitope on the Chlamydia trachomatis MOMP.
- To evaluate the potential of this epitope in a subunit vaccine strategy.
Main Methods:
- Monoclonal antibody L3-1 was used to map a B-cell epitope (AEFPLDIT) to variable sequence 3 of MOMP.
- Western blot, immunofluorescence, dot-blot, and ELISA assays were employed to assess antibody binding and epitope accessibility.
- In vivo and in vitro neutralization assays were conducted to evaluate the functional activity of the monoclonal antibody.
Main Results:
- A B-cell epitope, AEFPLDIT, was localized to variable sequence 3 of MOMP and recognized multiple C complex serovars.
- The epitope was confirmed to be surface-exposed on elementary bodies.
- The monoclonal antibody demonstrated in vivo neutralization of chlamydial infectivity without in vitro neutralization or toxicity.
Conclusions:
- The identified B-cell epitope on MOMP is surface-exposed and elicits neutralizing antibodies in vivo.
- Variable sequence 3 of MOMP, previously shown to induce T-cell responses, is a promising candidate for subunit vaccine development.
- Further investigation into incorporating this region into a Chlamydia trachomatis subunit vaccine is warranted.