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Functional and structural mapping of Chlamydia trachomatis species-specific major outer membrane protein epitopes by
E M Peterson1, X Cheng, B A Markoff
1Department of Pathology, University of California, Irvine 92717.
Abstract:
Three monoclonal antibodies (MAbs), E4, L1-4, and L1-24, to the major outer membrane protein (MOMP) of Chlamydia trachomatis were identified that neutralized in vitro the infectivity of members of the B- and C-related complex as well as the mouse pneumonitis strain. MAbs L1-4, L1-24, and E4 gave a strong signal in an indirect immunofluorescence assay and/or Western immunoblot with all serovars of the lymphogranuloma venereum and trachoma biovars and a weak signal with the mouse biovar. In addition, C. psittaci and C. pneumoniae were also weakly recognized by MAbs L1-4 and L1-24. As determined by the technique of pneumoniae were also weakly recognized by MAbs L1-4 and L1-24. As determined by by the technique of overlapping peptides, all three MAbs showed reactivity to variable domain (VD) IV of MOMP. While all three MAbs had different recognition patterns, all strongly bound to the peptides TLNPTI and LNPTIA within the species-conserved region of VD IV. MAb E4 also recognized the peptide SATAIF in the subspecies region of VD IV. Peptides corresponding to VD IV of MOMP were synthesized and used in competitive inhibition experiments to determine the functional location of the epitope recognized by these three MAbs. Both the serological and neutralizing activities of MAb E4 were inhibited by the peptides ATAIFDTTTLNPTIAG and FDTTTLNPTIAG; however, none of the peptides made to the VD IV region blocked the neutralizing activity of MAbs L1-4 and L1-24. Therefore, the neutralizable domain of the epitope recognized by MAb E4 is contiguous and may be an important candidate for inclusion in a subunit vaccine.
Insights
Three monoclonal antibodies targeting Chlamydia trachomatis major outer membrane protein (MOMP) neutralized bacterial infectivity. MAb E4’s epitope within variable domain IV is a potential subunit vaccine candidate due to its contiguous, neutralizable nature.
Area of Science:
- Immunology
- Microbiology
- Vaccine Development
Background:
- Chlamydia trachomatis is a significant human pathogen.
- The major outer membrane protein (MOMP) is a key target for immune responses.
- Developing effective vaccines against Chlamydia trachomatis remains a priority.
Purpose of the Study:
- To identify and characterize monoclonal antibodies (MAbs) targeting Chlamydia trachomatis MOMP.
- To investigate the neutralizing capabilities and epitope mapping of these MAbs.
- To evaluate MAb E4 as a potential candidate for a subunit vaccine.
Main Methods:
- Production and characterization of three MAbs (E4, L1-4, L1-24) against Chlamydia trachomatis MOMP.
- In vitro infectivity neutralization assays.
- Indirect immunofluorescence and Western immunoblotting for serovar reactivity.
- Overlapping peptide synthesis and competitive inhibition assays for epitope mapping.
Main Results:
- MAbs E4, L1-4, and L1-24 neutralized infectivity of B- and C-related complex and mouse pneumonitis strains.
- All MAbs recognized variable domain (VD) IV of MOMP, with specific peptide binding identified.
- MAb E4's neutralizing activity was blocked by specific peptides in VD IV, suggesting a contiguous, neutralizable epitope.
- MAbs L1-4 and L1-24 neutralizing activity was not blocked by VD IV peptides.
Conclusions:
- Monoclonal antibodies targeting MOMP's VD IV can neutralize Chlamydia trachomatis infectivity.
- MAb E4 recognizes a contiguous, neutralizable epitope within MOMP's VD IV.
- This epitope is a promising candidate for inclusion in a Chlamydia trachomatis subunit vaccine.