title: Cloning of a gene fragment encoding bovine complement component C3d with expression and characterization of derived fusion proteins.
abstract: The gene fragment coding for bovine C3d gene (boC3d) was cloned and expressed as a component of fusion proteins destined for use in vaccine studies in cattle, and for in vitro experiments. This fragment of complement protein C3 (C3d) has been shown to enhance B cell responses when complexed with antigen. Three potential vaccine constructs were engineered to contain one, two or three boC3d units linked to a fragment of the leukotoxin of Mannheimia haemolytica A1, an economically important pathogen of cattle that causes a fibrinous pneumonia in calves. A recombinant biotinylated boC3d protein (for use in in vitro studies) was generated by endogenous biotinylation in Escherichia coli by means of the BirA holoenzyme synthetase. All recombinant proteins incorporated polyhistidine tags and were purified by nickel-agarose chromatography, then analyzed by SDS-PAGE and Western immunoblot. The identity of boC3d was confirmed by mass spectrometry, since monoclonal antibodies to boC3d were not available. To date, published research into the adjuvant activities of C3d has been limited to experiments in mice and rabbits, using antigens unrelated to diseases occurring naturally in these species. The boC3d fusion proteins expressed in this study will provide the basis for immunization trials in cattle and studies of receptor binding and cell activation of bovine lymphocytes.
authors.affiliation: Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Firth
authors.forename: D
authors.initials: D
authors.lastname: Prando Moore
authors.forename: Yanlong
authors.initials: Y
authors.lastname: Pei
authors.forename: Patricia E
authors.initials: PE
authors.lastname: Shewen
authors.forename: Reggie Y C
authors.initials: RY
authors.lastname: Lo
authors.forename: Dongwan
authors.initials: D
authors.lastname: Yoo
authors.forename: Douglas C
authors.initials: DC
authors.lastname: Hodgins
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology; D001428:Bacterial Vaccines / Q000235:genetics / Q000276:immunology; D001483:Base Sequence; D015153:Blotting, Western / Q000662:veterinary; D002417:Cattle / Q000235:genetics* / Q000276:immunology*; D003001:Cloning, Molecular; D015933:Complement C3d / Q000096:biosynthesis / Q000235:genetics* / Q000276:immunology*; D005260:Female; D006460:Hemolysin Proteins / Q000235:genetics / Q000276:immunology; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D017422:Sequence Analysis, DNA
chemical_list: D001426:Bacterial Proteins; D001428:Bacterial Vaccines; D006460:Hemolysin Proteins; D011993:Recombinant Fusion Proteins; C102677:lktA protein, bacteria; D015933:Complement C3d