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Updated: Aug 10, 2026
Immuno-fluorescence Assay of Leptospiral Surface-exposed Proteins
Published on: July 1, 2011
Conformational epitope mapping of OmpC, a major cell surface antigen from Salmonella typhi
A Arockiasamy1, G S Murthy, M R Rukmini
1Department of Genetic Engineering, School of Biotechnology, Madurai Kamaraj University, 625 021, India.
Abstract:
The outer membrane protein OmpC, a trimer made of 16 stranded beta-barrel monomers, is a major cell surface antigen from the human pathogen Salmonella typhi. The relative stability of the epitopes recognising a Salmonella specific MAb (referred as MPN5) and an Enterobacteria specific MAb (referred as P7D8) and the role of the trimeric organisation has been probed using gel electrophoresis and monoclonal antibodies. The assembly of the trimer and the stability of the beta-barrel are found to be important for epitope presentation. The Salmonella specific conformational epitope is found to be more stable than the Enterobacteria specific one. The important residues of the Salmonella specific (Asp 25 of loop 1, Asp 340 of loop 8, Lys 334 of loop 8, and Tyr 210 of loop 5) and the Enterobacteria specific (Asp 25 of loop 1, Tyr 210 of loop 5, and Lys 152 of loop 4) conformational epitope have been identified using monoclonal antibodies, chemical modification, and solid phase binding methods.
Insights
The outer membrane protein OmpC
Area of Science:
- Microbiology and immunology, focusing on bacterial outer membrane proteins and antigenicity.
Background:
- OmpC is a major cell surface antigen of Salmonella typhi, a human pathogen.
- OmpC forms a trimer composed of 16-stranded beta-barrel monomers.
Purpose of the Study:
- To investigate the stability of Salmonella-specific and Enterobacteria-specific epitopes on OmpC.
- To determine the role of OmpC's trimeric organization in epitope presentation.
Main Methods:
- Gel electrophoresis and monoclonal antibodies were used to probe epitope stability.
- Chemical modification and solid-phase binding assays identified key epitope residues.
Main Results:
- OmpC trimer assembly and beta-barrel stability are crucial for epitope presentation.
- The Salmonella-specific conformational epitope is more stable than the Enterobacteria-specific one.
- Specific amino acid residues in OmpC loops were identified as important for each epitope.
Conclusions:
- The structural integrity of OmpC is essential for the presentation of its conformational epitopes.
- Differential stability of epitopes may have implications for diagnostic and therapeutic strategies against Salmonella typhi.
