title: Surface expression of Helicobacter pylori HpaA adhesion antigen on Vibrio cholerae, enhanced by co-expressed enterotoxigenic Escherichia coli fimbrial antigens.
abstract: Helicobacter pylori infection can cause peptic ulceration and is associated with gastric adenocarcinoma. This study aimed to construct and characterize a non-virulent Vibrio cholerae O1 strain, which grows more rapidly than H. pylori, as vector for H. pylori antigens for possible use as a vaccine strain against H. pylori. This was done by recombinant expression of the H. pylori adhesion antigen HpaA alone or, as a proof of principle, together with different colonization factor (CF) antigens of enterotoxigenic Escherichia coli (ETEC) which may enhance immune responses against HpaA. A recombinant V. cholerae strain co-expressing HpaA and a fimbrial CF antigens CFA/I or CS5, but not the non-fimbrial CF protein CS6, was shown to express larger amounts of HpaA on the surface when compared with the same V. cholerae strain expressing HpaA alone. Mutations in the CFA/I operon showed that the chaperon, possibly together with the usher, was involved in enhancing the surface expression of HpaA. Oral immunization of mice with formaldehyde-inactivated recombinant V. cholerae expressing HpaA alone or together with CFA/I induced significantly higher serum antibody responses against HpaA than mice similarly immunized with inactivated HpaA-expressing H. pylori bacteria. Our results demonstrate that a non-virulent V. cholerae strain can be engineered to allow strong surface expression of HpaA, and that the expression can be further increased by co-expressing it with ETEC fimbrial antigens. Such recombinant V. cholerae strains expressing HpaA, and possibly also other H. pylori antigens, may have the potential as oral inactivated vaccine candidates against H. pylori.
authors.affiliation: Department of Microbiology and Immunology, Institute of Biomedicine, University of Gothenburg Vaccine Research Institute (GUVAX), University of Gothenburg, S-40530 Göteborg, Sweden. Electronic address: joshua.tobias@meduniwien.ac.at.
authors.forename: Joshua
authors.initials: J
authors.lastname: Tobias
authors.affiliation: Department of Microbiology and Immunology, Institute of Biomedicine, University of Gothenburg Vaccine Research Institute (GUVAX), University of Gothenburg, S-40530 Göteborg, Sweden.
authors.forename: Michael
authors.initials: M
authors.lastname: Lebens
authors.affiliation: Institute of Molecular Biology, Umeå University, S-90187 Umeå, Sweden.
authors.forename: Sun Nyunt
authors.initials: SN
authors.lastname: Wai
authors.affiliation: Department of Microbiology and Immunology, Institute of Biomedicine, University of Gothenburg Vaccine Research Institute (GUVAX), University of Gothenburg, S-40530 Göteborg, Sweden.
authors.forename: Jan
authors.initials: J
authors.lastname: Holmgren
authors.affiliation: Department of Microbiology and Immunology, Institute of Biomedicine, University of Gothenburg Vaccine Research Institute (GUVAX), University of Gothenburg, S-40530 Göteborg, Sweden.
authors.forename: Ann-Mari
authors.initials: AM
authors.lastname: Svennerholm
mesh_terms: D018829:Adhesins, Bacterial / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology; D000917:Antibody Formation; D001422:Bacterial Adhesion / Q000235:genetics / Q000276:immunology; D001425:Bacterial Outer Membrane Proteins; D001428:Bacterial Vaccines / Q000276:immunology; D004269:DNA, Bacterial; D054307:Enterotoxigenic Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000276:immunology; D005260:Female; D036781:Fimbriae Proteins / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D010861:Fimbriae, Bacterial / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D016481:Helicobacter Infections / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control; D016480:Helicobacter pylori / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D064789:Immunity, Heterologous / Q000235:genetics / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D015202:Protein Engineering; D011994:Recombinant Proteins / Q000096:biosynthesis; D014614:Vaccines, Synthetic / Q000276:immunology; D014734:Vibrio cholerae / Q000235:genetics / Q000276:immunology* / Q000378:metabolism
chemical_list: D018829:Adhesins, Bacterial; D000907:Antibodies, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001428:Bacterial Vaccines; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D011994:Recombinant Proteins; D014614:Vaccines, Synthetic; C022924:colonization factor antigens; C450844:enterotoxigenic invasive protein A, E coli; D036781:Fimbriae Proteins; C095977:adhesin A, Helicobacter
keywords: Co-expression; ETEC; H. pylori; Heterologous surface expression; V. cholerae