title: [Enterotoxigenic Escherichia coli heat-labile enterotoxin B subunit can efficiently induce and enhance the mucosal immune response to enterovirus 71].
abstract: OBJECTIVE
  To detect the immunogenicity of enterotoxigenic Escherichia coli heat-labile enterotoxin B subunit (LTB) and evaluate the immune effect of enterovirus 71 (EV71) capsid protein VP1 together with LTB by the intranasal route.
  
  
  METHODS
  The LTB gene was cloned into the plasmid pET32a. The 6×His-LTB fusion protein was purified with Ni(2+)-NTA resin and used to vaccinate the New Zealand white rabbits to prepare the LTB-specific antiserum. The titer was determined by ELISA. BALB/c mice were immunized with normal saline, purified EV71 VP1 alone and EV71 VP1 together with LTB by the intranasal drip respectively. The sera as well as lung and intestinal mucosa lavage fluids were collected and determined for IgG and secretory IgA (sIgA) by indirect ELISA.
  
  
  RESULTS
  Recombinant plasmid pET32a-LTB was constructed successfully. The expressed fusion protein 6×His-LTB, with a relative molecular mass of about 30 000, existed mostly in a form of inclusion body. The serum antibody titer induced with it was 1:125 000 in the New Zealand white rabbits. The levels of specific IgG and sIgA in mice immunized with EV71 VP1 plus LTB were significantly higher than those in the ones with EV71 VP1 alone and normal saline.
  
  
  CONCLUSIONS
  Fusion protein 6×His-LTB was successfully expressed in E.coli BL21 (DE3) and showed both good immunogenicity and adjuvant activity. The LTB can efficiently enhance specific serum antibody response and induce mucosal immune response by intranasal drip.
authors.affiliation: Key Laboratory of Biochemistry and Molecular Biology, Chongqing Medical University, Chongqing 400016, China.
authors.forename: Tingting
authors.initials: T
authors.lastname: Xie
authors.affiliation: Key Laboratory of Biochemistry and Molecular Biology, Chongqing Medical University, Chongqing 400016, China.
authors.forename: Qiongwen
authors.initials: Q
authors.lastname: Hu
authors.affiliation: Key Laboratory of Biochemistry and Molecular Biology, Molecular Medicine and Cancer Research Center, Chongqing Medical University, Chongqing 400016, China.
authors.forename: Yongping
authors.initials: Y
authors.lastname: Ma
mesh_terms: D000818:Animals; D001427:Bacterial Toxins / Q000235:genetics / Q000276:immunology*; D036022:Capsid Proteins / Q000276:immunology*; D054307:Enterotoxigenic Escherichia coli / Q000472:pathogenicity*; D004768:Enterotoxins / Q000235:genetics / Q000276:immunology*; D029821:Enterovirus A, Human / Q000276:immunology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000276:immunology*; D018928:Immunity, Mucosal; D007071:Immunoglobulin A, Secretory / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000276:immunology / Q000302:isolation & purification
chemical_list: D001427:Bacterial Toxins; D036022:Capsid Proteins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; D007071:Immunoglobulin A, Secretory; D007074:Immunoglobulin G; D011993:Recombinant Fusion Proteins; C027538:heat-labile enterotoxin, E coli