Oral immunization of piglets with recombinant F4 fimbrial adhesin FaeG monomers induces a mucosal and systemic F4-specific immune response.
The importance of adhesins in the pathogenicity of several bacteria resulted in studies on their usefulness in vaccines. In this study, the gene of the F4(K88)-fimbrial adhesin FaeG of the pathogenic enterotoxigenic Escherichia coli (ETEC) strain GIS26 was cloned in the pET30Ek-LIC vector and expressed with an N-terminal His- and S-tag in the cytoplasm of BL21(DE3). Recombinant FaeG (rFaeG) subunits were isolated from insoluble cytoplasmic aggregates and refolded into a native-like F4 receptor (F4R)-binding conformation. Indeed, the presence of conformational epitopes was shown by ELISA and the ability to bind the F4R was observed by inhibiting the adhesion of F4+ ETEC to F4R+ villi with increasing concentrations of native-like refolded rFaeG subunits. The rFaeG subunits appear as monomers, whereas the purified F4 fimbriae are multimers. Oral immunization of newly weaned piglets with native-like rFaeG induced a mucosal and systemic F4-specific immune response, significantly reducing F4+ E. coli excretion from 2 till 5 days following challenge infection. However, improvement of stability and immunogenicity of rFaeG is necessary since a higher F4-specific response was obtained following immunization with purified F4 fimbriae. Furthermore, the N-terminal fusion of a His- and S-tag was not detrimental for binding the F4R, supporting the use of FaeG as mucosal carrier. In conclusion, oral immunization with a recombinant fimbrial adhesin subunit of Escherichia coli induces a mucosal and systemic fimbriae-specific immune response.
Laboratory of Veterinary Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium. Frank.Verdonck@uGent.be
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Verdonck
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Cox
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Van der Stede
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BM
Goddeeris
D018829:Adhesins, Bacterial / Q000008:administration & dosage / Q000737:chemistry / Q000276:immunology*; D018830:Adhesins, Escherichia coli / Q000008:administration & dosage / Q000737:chemistry / Q000276:immunology*; D000284:Administration, Oral; D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis / Q000096:biosynthesis*; D000917:Antibody Formation / Q000276:immunology*; D001428:Bacterial Vaccines / Q000008:administration & dosage / Q000737:chemistry / Q000276:immunology*; D015153:Blotting, Western; D004797:Enzyme-Linked Immunosorbent Assay; D004926:Escherichia coli / Q000737:chemistry / Q000276:immunology; D004927:Escherichia coli Infections / Q000276:immunology / Q000517:prevention & control; D005243:Feces / Q000382:microbiology; D018928:Immunity, Mucosal / Q000276:immunology*; D007114:Immunization; D007070:Immunoglobulin A / Q000032:analysis / Q000096:biosynthesis; D007074:Immunoglobulin G / Q000032:analysis / Q000096:biosynthesis; D007075:Immunoglobulin M / Q000032:analysis / Q000096:biosynthesis; D013552:Swine / Q000276:immunology; D014614:Vaccines, Synthetic / Q000032:analysis / Q000737:chemistry / Q000276:immunology
D018829:Adhesins, Bacterial; D018830:Adhesins, Escherichia coli; D000907:Antibodies, Bacterial; D001428:Bacterial Vaccines; C494388:FaeG protein, E coli; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D014614:Vaccines, Synthetic