title: Construction and evaluation of a fluorescence-based live attenuated Escherichia coli delivery system for generating oral vaccine candidate.
abstract: Enter toxigenic Escherichia coli (ETEC) is a major pathogen of swine industry that can have a substantial impact on morbidity and mortality. Therefore, it is necessary to develop effective vaccines for the prevention of ETEC infection. Live attenuated bacteria delivery system are effective tools for mucosal immunization. The purpose of this study was to construct a novel delivery system that can present the LTR192G-STb fusion protein as oral vaccine candidate. Firstly, the PRPL-mKate2 fluorescent cassette was inserted into the genome (yaiT pseudogene) of an attenuated E. coli by homologous recombination methods to construct the delivery system O142(yaiT::PRPL-mKate2). Secondly, the oral vaccine O142(yaiT:: LT192-STb) (ER-B) was derived for replacing the PRPL-mKate2 by LT192-STb fusion gene, and then it was tested for its feasibility as oral vaccine candidate. Subsequently, BALB/c mice were orogastrically immunized with ER-B. Results showed that mice orally immunized with ER-B produced high levels of specific IgA and IgG antibodies. The induced antibodies demonstrated neutralizing effects to enter toxins LT and STb. In addition, results of cellular immune responses showed that stimulation index values of immunized mice were significantly higher than the control group (P < 0.05) and with a marked shift towards Th 2 immunity. These data indicated that the recombinant E. coli ER-B could be a valuable candidate of future vaccines against ETEC infection.
authors.affiliation: Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang, 150030, People's Republic of China.
authors.forename: Wenxin
authors.initials: W
authors.lastname: Liu
authors.forename: Xingyue
authors.initials: X
authors.lastname: Li
authors.forename: Jun
authors.initials: J
authors.lastname: Bao
authors.forename: Weikun
authors.initials: W
authors.lastname: Guan
authors.forename: Zhiteng
authors.initials: Z
authors.lastname: Zhao
authors.forename: Chaowen
authors.initials: C
authors.lastname: Yuan
authors.forename: Jie
authors.initials: J
authors.lastname: Tang
authors.forename: Dongfang
authors.initials: D
authors.lastname: Shi
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis / Q000097:blood; D057134:Antibodies, Neutralizing / Q000032:analysis / Q000097:blood; D001427:Bacterial Toxins / Q000235:genetics / Q000276:immunology*; D049109:Cell Proliferation; D004768:Enterotoxins / Q000235:genetics / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D004926:Escherichia coli / Q000235:genetics / Q000276:immunology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000276:immunology*; D022361:Escherichia coli Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D005243:Feces / Q000737:chemistry; D005453:Fluorescence; D017930:Genes, Reporter; D007070:Immunoglobulin A / Q000032:analysis / Q000097:blood; D007074:Immunoglobulin G / Q000032:analysis / Q000097:blood; D008807:Mice, Inbred BALB C; D044967:Serum / Q000737:chemistry; D013601:T-Lymphocytes / Q000276:immunology; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology
chemical_list: D000907:Antibodies, Bacterial; D057134:Antibodies, Neutralizing; D001427:Bacterial Toxins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; D022361:Escherichia coli Vaccines; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D014613:Vaccines, Attenuated; D014614:Vaccines, Synthetic; C034151:heat stable toxin (E coli); C027538:heat-labile enterotoxin, E coli