title: Immunogenicity and Protective Efficacy against Enterotoxigenic Escherichia coli Colonization following Intradermal, Sublingual, or Oral Vaccination with EtpA Adhesin.
abstract: Enterotoxigenic Escherichia coli (ETEC) strains are a common cause of diarrhea. Extraordinary antigenic diversity has prompted a search for conserved antigens to complement canonical approaches to ETEC vaccine development. EtpA, an immunogenic extracellular ETEC adhesin relatively conserved in the ETEC pathovar, has previously been shown to be a protective antigen following intranasal immunization. These studies were undertaken to explore alternative routes of EtpA vaccination that would permit use of a double mutant (R192G L211A) heat-labile toxin (dmLT) adjuvant. Here, oral vaccination with EtpA adjuvanted with dmLT afforded significant protection against small intestinal colonization, and the degree of protection correlated with fecal IgG, IgA, or total fecal antibody responses to EtpA. Sublingual vaccination yielded compartmentalized mucosal immune responses with significant increases in anti-EtpA fecal IgG and IgA, and mice vaccinated via this route were also protected against colonization. In contrast, while intradermal (i.d.) vaccination achieved high levels of both serum and fecal antibodies against both EtpA and dmLT, mice vaccinated via the i.d. route were not protected against subsequent colonization and the avidity of serum IgG and IgA EtpA-specific antibodies was significantly lower after i.d. immunization compared to other routes. Finally, we demonstrate that antiserum from vaccinated mice significantly impairs binding of LT to cognate GM1 receptors and shows near complete neutralization of toxin delivery by ETEC in vitro Collectively, these data provide further evidence that EtpA could complement future vaccine strategies but also suggest that additional effort will be required to optimize its use as a protective immunogen.
authors.affiliation: Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, USA.
authors.forename: Qingwei
authors.initials: Q
authors.lastname: Luo
authors.affiliation: Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, USA.
authors.forename: Tim J
authors.initials: TJ
authors.lastname: Vickers
authors.affiliation: Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, USA Molecular Microbiology and Microbial Pathogenesis Program, Washington University School of Medicine, Saint Louis, Missouri, USA Medicine Service, Veterans Affairs Medical Center, Saint Louis, Missouri, USA jflecken@wustl.edu.
authors.forename: James M
authors.identifier: 0000-0002-1148-697X
authors.initials: JM
authors.lastname: Fleckenstein
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage / Q000235:genetics; D000284:Administration, Oral; D000286:Administration, Sublingual; D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis; D057134:Antibodies, Neutralizing / Q000032:analysis / Q000097:blood; D001427:Bacterial Toxins / Q000008:administration & dosage / Q000235:genetics; D004195:Disease Models, Animal; D054307:Enterotoxigenic Escherichia coli / Q000276:immunology*; D004768:Enterotoxins / Q000008:administration & dosage / Q000235:genetics; D004927:Escherichia coli Infections / Q000517:prevention & control*; D029968:Escherichia coli Proteins / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D022361:Escherichia coli Vaccines / Q000008:administration & dosage* / Q000276:immunology*; D005243:Feces / Q000737:chemistry; D005260:Female; D007070:Immunoglobulin A / Q000032:analysis / Q000097:blood; D007074:Immunoglobulin G / Q000032:analysis / Q000097:blood; D007271:Injections, Intradermal; D008562:Membrane Glycoproteins / Q000276:immunology*; D051379:Mice; D050505:Mutant Proteins / Q000008:administration & dosage / Q000235:genetics
chemical_list: D000276:Adjuvants, Immunologic; D000907:Antibodies, Bacterial; D057134:Antibodies, Neutralizing; D001427:Bacterial Toxins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; D022361:Escherichia coli Vaccines; C510011:EtpA protein, E coli; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D008562:Membrane Glycoproteins; D050505:Mutant Proteins; C027538:heat-labile enterotoxin, E coli