en 23626873 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. Bordetella pertussis, Filamentous hemagglutinin, Immunodominant, Prokaryotic expression, Recombinant antigen 20 28 https://www.ajmb.org/En/Article.aspx?id=105 https://www.ajmb.org/PDF/En/FullText/105.pdf HosseinAsgarian-OmranDepartment of Immunology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran238Ali AkbarAmirzargarDepartment of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran179MohammadArjmandDepartment of Biochemistry, Pasteur Institute of Iran, Tehran, Iran445MohammadrezaEshraghianDepartment of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran446BehroozNikbinDepartment of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran447SaeidEshraghiDepartment of Microbiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran448MarziehMahdaviMonoclonal Antibody Research Center, Avicenna Research Institute, ACECR, Tehran, Iran449JalalKhoshnoodiDepartment of Immunology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran168MahmoodJeddi-TehraniMonoclonal Antibody Research Center, Avicenna Research Institute, ACECR, Tehran, Iran15HodjattallahRabbaniMonoclonal Antibody Research Center, Avicenna Research Institute, ACECR, Tehran, Iran24FazelShokriMonoclonal Antibody Research Center, Avicenna Research Institute, ACECR, Tehran, Iran5