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Electrophoretic mobility and immune response of outer membrane proteins of Vibrio cholerae O139
S Pal1, D Sasmal, B Guhathakurta
1Department of Biochemistry, National Institute of Cholera and Enteric Diseases, Calcutta, India.
Abstract:
The outer membrane (OM) protein components of a Vibrio cholerae O1 and four V. cholerae O139 strains, collected from cholera patients, were analysed by SDS-PAGE. A protein of 69 kDa molecular mass was observed only when the OMPs were prepared from strains grown in synthetic broth. As a result of passage in the rabbit ileal loop (RIL), virulence was enhanced, and a protein component around 18 kDa of the V. cholerae O139 OM became the major protein component. On immunoblot analysis with rabbit antiserum against V. cholerae O139 OM, it was shown that, apart from the major protein component of V. cholerae O1 OM of around 45 kDa and that of V. cholerae O139 OM of around 38 kDa, all other minor protein components were cross-reactive between the two serogroups. In immunoblot assays with convalescent sera obtained from V. cholerae O139-infected patients, it was observed that in addition to the lipopolysaccharide (LPS)-induced antibody, only the 38 kDa major protein component elicited considerable levels of antibody in the patient. Minor OM components of 18 kDa were detected in the immunoblot analysis by LPS-directed antibody, however, as the OM proteins are known to be associated with LPS.
Insights
Outer membrane proteins of Vibrio cholerae O1 and O139 strains were analyzed. A specific 18 kDa protein component in V. cholerae O139 outer membrane was identified as a major antigen in patients.
Area of Science:
- Microbiology
- Immunology
- Protein Biochemistry
Background:
- Vibrio cholerae causes cholera, a significant public health concern.
- Outer membrane proteins (OMPs) play crucial roles in bacterial pathogenesis and host immune responses.
- Understanding the antigenic properties of V. cholerae OMPs is vital for vaccine development and diagnostics.
Purpose of the Study:
- To characterize the outer membrane protein components of Vibrio cholerae O1 and O139 serogroups.
- To investigate changes in OMP profiles following in vivo passage and their immunogenicity.
- To identify specific OMP antigens recognized by patient sera.
Main Methods:
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for OMP separation.
- Immunoblot analysis using antisera against V. cholerae O139 OMPs.
- Immunoblot assays with convalescent sera from V. cholerae O139-infected patients.
Main Results:
- A 69 kDa OMP was detected in strains grown in synthetic broth.
- Passage in the rabbit ileal loop (RIL) enhanced virulence and led to an 18 kDa protein becoming a major component in V. cholerae O139 OMs.
- Major OMPs were ~45 kDa for V. cholerae O1 and ~38 kDa for V. cholerae O139; minor components were cross-reactive.
- The 38 kDa OMP of V. cholerae O139 elicited significant antibody response in infected patients, alongside LPS-induced antibodies.
Conclusions:
- Specific outer membrane proteins of Vibrio cholerae O139, particularly the 38 kDa component, are major targets of the host immune response during infection.
- The 18 kDa OMP component, associated with LPS, is also recognized by patient antibodies.
- These findings highlight potential vaccine candidates and diagnostic markers for cholera.