Expression, Purification and Characterization of Three Overlapping Immunodominant Recombinant Fragments from Bordetella pertussis Filamentous Hemagglutinin

Background: Filamentous hemagglutinin (FHA) is one of the most important immunoprotective antigens of Bordetella pertussis (B.pertussis) and a major component of the acellular pertussis vaccine. In the present study, three overlapping recombinant fragments from the immunodominant region of FHA were produced and their immunogenicity was investigated. Methods: Three overlapping coding sequences of FHA antigen were amplified from B.pertussis genomic DNA by PCR. Amplified fragments were expressed in Escherichia coli (E. coli) BL21(DE3) strain and purified through His-tag using Nickel-based chromatography. Purified fragments were characterized by SDS-PAGE and Western blotting techniques. In vitro peripheral blood mononuclear cells (PBMC) proliferation and IFN-γ production were assessed in a limited number of healthy adults vaccinated with a commercial acellular pertussis vaccine in response to all purified FHA fragments by H3-Thymidine incorporation and ELISA, respectively. Results: Recombinant FHA segments were successfully cloned and produced at high levels in E. coli BL21(DE3). SDS-PAGE and Western blot analyses confirmed their purity and reactivity. All three recombinant fragments together with a commercial native FHA were able to induce in vitro PBMC proliferation and IFN-γ production. Conclusion: Our preliminary results suggest that these overlapping recombinant FHA fragments are immunogenic and may prove to be immuno-protective.