title: Construction of non-toxic Escherichia coli and Vibrio cholerae strains expressing high and immunogenic levels of enterotoxigenic E. coli colonization factor I fimbriae.
abstract: To express high quantities of colonization factor antigen I (CFA/I) derived from enterotoxigenic Escherichia coli (ETEC) for use in ETEC vaccines, the entire CFA/I operon consisting of four genes (cfa-A, -B, -C, -E) was cloned into plasmid expression vectors that could be maintained either with or without antibiotic selection. Expression from the powerful tac promoter was under the control of the lacIq repressor present on the plasmids. Fimbriae were expressed on the surface of both a non-toxigenic E. coli K12 strain and a non-toxigenic strain of Vibrio cholerae following induction with isopropyl-beta-D-thiogalactopyranoside (IPTG). It was found that the recombinant E. coli strains expressed up to 16-fold higher levels of CFA/I fimbriae compared to a reference strain which had previously been shown to be among the highest natural producers of the CFA/I fimbriae among tested wild type ETEC strains. Oral immunization with formalin-killed recombinant E. coli bacteria over-expressing CFA/I induced significantly higher serum IgA and IgG+M antibodies responses compared to the reference strain. Oral immunization with formalin-killed recombinant V. cholerae bacteria also induce strong CFA/I-specific serum IgA and IgG+M responses. We conclude that our constructs may be useful as candidate strains in an oral killed CF-ETEC vaccine.
authors.affiliation: Institute of Biomedicine, Department of Microbiology and Immunology, The Sahlgrenska Academy of Göteborg University, S-40530 Göteborg, Sweden. Joshua.Tobias@microbio.gu.se
authors.forename: Joshua
authors.initials: J
authors.lastname: Tobias
authors.forename: Michael
authors.initials: M
authors.lastname: Lebens
authors.forename: Ingrid
authors.initials: I
authors.lastname: Bölin
authors.forename: Gudrun
authors.initials: G
authors.lastname: Wiklund
authors.forename: Ann-Mari
authors.initials: AM
authors.lastname: Svennerholm
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood*; D001428:Bacterial Vaccines / Q000008:administration & dosage / Q000276:immunology; D054307:Enterotoxigenic Escherichia coli / Q000276:immunology*; D004926:Escherichia coli / Q000276:immunology / Q000378:metabolism*; D004927:Escherichia coli Infections / Q000097:blood / Q000276:immunology*; D005260:Female; D036781:Fimbriae Proteins / Q000096:biosynthesis / Q000235:genetics*; D010861:Fimbriae, Bacterial / Q000235:genetics*; D005557:Formaldehyde; D007114:Immunization; D007115:Immunization Schedule; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D051379:Mice; D008807:Mice, Inbred BALB C; D009876:Operon; D010957:Plasmids; D015202:Protein Engineering; D011994:Recombinant Proteins / Q000096:biosynthesis; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000276:immunology; D014734:Vibrio cholerae / Q000276:immunology / Q000378:metabolism*
chemical_list: D000907:Antibodies, Bacterial; D001428:Bacterial Vaccines; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D011994:Recombinant Proteins; D014614:Vaccines, Synthetic; C022924:colonization factor antigens; D036781:Fimbriae Proteins; D005557:Formaldehyde