title: Toxicity and immunogenicity of Enterotoxigenic Escherichia coli heat-labile and heat-stable toxoid fusion 3xSTa(A14Q)-LT(S63K/R192G/L211A) in a murine model.
abstract: Diarrhea is the second leading cause of death to young children. Enterotoxigenic Escherichia coli (ETEC) are the most common bacteria causing diarrhea. Adhesins and enterotoxins are the virulence determinants in ETEC diarrhea. Adhesins mediate bacterial attachment and colonization, and enterotoxins including heat-labile (LT) and heat-stable type Ib toxin (STa) disrupt fluid homeostasis in host cells that leads to fluid hyper-secretion and diarrhea. Thus, adhesins and enterotoxins have been primarily targeted in ETEC vaccine development. A recent study reported toxoid fusions with STa toxoid (STa(P13F)) fused at the N- or C-terminus, or inside the A subunit of LT(R192G) elicited neutralizing antitoxin antibodies, and suggested application of toxoid fusions in ETEC vaccine development (Liu et al., Infect. Immun. 79:4002-4009, 2011). In this study, we generated a different STa toxoid (STa(A14Q)) and a triple-mutant LT toxoid (LT(S63K/R192G/L211A), tmLT), constructed a toxoid fusion (3xSTa(A14Q)-tmLT) that carried 3 copies of STa(A14Q) for further facilitation of anti-STa immunogenicity, and assessed antigen safety and immunogenicity in a murine model to explore its potential for ETEC vaccine development. Mice immunized with this fusion antigen showed no adverse effects, and developed antitoxin antibodies particularly through the IP route. Anti-LT antibodies were detected and were shown neutralizing against CT in vitro. Anti-STa antibodies were also detected in the immunized mice, and serum from the IP immunized mice neutralized STa toxin in vitro. Data from this study indicated that toxoid fusion 3xSTa(A14Q)-tmLT is safe and can induce neutralizing antitoxin antibodies, and provided helpful information for vaccine development against ETEC diarrhea.
authors.affiliation: Veterinary & Biomedical Sciences Department /The Center for Infectious Disease Research & Vaccinology, South Dakota State University, Brookings, South Dakota, United States of America.
authors.forename: Chengxian
authors.initials: C
authors.lastname: Zhang
authors.forename: David E
authors.initials: DE
authors.lastname: Knudsen
authors.forename: Mei
authors.initials: M
authors.lastname: Liu
authors.forename: Donald C
authors.initials: DC
authors.lastname: Robertson
authors.forename: Weiping
authors.initials: W
authors.lastname: Zhang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood / Q000276:immunology; D057134:Antibodies, Neutralizing / Q000097:blood / Q000276:immunology; D001427:Bacterial Toxins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D004195:Disease Models, Animal; D054307:Enterotoxigenic Escherichia coli / Q000235:genetics / Q000276:immunology*; D004768:Enterotoxins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D004927:Escherichia coli Infections / Q000276:immunology / Q000517:prevention & control; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D005260:Female; D015870:Gene Expression; D023061:Gene Order; D005822:Genetic Vectors / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D009500:Neutralization Tests; D011993:Recombinant Fusion Proteins; D016415:Sequence Alignment; D014121:Toxoids / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000633:toxicity*
chemical_list: D000907:Antibodies, Bacterial; D057134:Antibodies, Neutralizing; D001427:Bacterial Toxins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; D011993:Recombinant Fusion Proteins; D014121:Toxoids; C034151:heat stable toxin (E coli)