IAI Accepts, published online ahead of print on 26 October 2009

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Google Scholar Articles by Zhang, W. Articles by Robertson, D. C. PubMed PubMed Citation Articles by Zhang, W. Articles by Robertson, D. C.

 Previous Article  |  Next Article 

Infect. Immun. doi:10.1128/IAI.00497-09
Copyright (c) 2009, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

Genetic fusions of LT_AB and STa toxoids of porcine enterotoxigenic Escherichia coli (ETEC) elicited neutralizing anti-LT and anti-STa antibodies

Weiping Zhang^*, Chengxian Zhang, David H. Francis, Ying Fang, David Knudsen, James P. Nataro, and Donald C. Robertson

Department of Veterinary Science/The Center for Infectious Disease Research & Vaccinology, South Dakota State University, Brookings, SD; Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MA; Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, KS

^* To whom correspondence should be addressed. Email: weiping.zhang{at}sdstate.edu.

Enterotoxigenic Escherichia coli (ETEC) strains are a major cause of diarrhea disease in humans and farm animals. E. coli fimbriae or colonization factor antigens (CFAs) and enterotoxins including heat-labile (LT) and heat-stable (ST) are the key virulence factors in ETEC diarrhea. Unlike fimbriae or LT, STa has not been much included as an antigen in vaccine development against ETEC diarrhea because of its poor immunogenicity. STa becomes immunogenic only after being coupled with a strongly immunogenic carrier protein. However, native or shorter STa antigens either had to retain toxic activity in order to become antigenic or elicited anti-STa antibodies that were not sufficiently protective. In this study, we genetically mutated porcine LT (pLT) gene for a pLT_192(RG) toxoid and STa (pSTa) gene for three full-length pSTatoxoids [STa_11(NK), STa_12(PF), and STa_13(AQ)], and used the full-length pLT₁₉₂ as an adjuvant to carry the pSTatoxoid for ‘pLT₁₉₂:pSTa-toxoid’ fusion antigens. Rabbits immunized with ‘pLT₁₉₂:pSTa₁₂’ or ‘pLT₁₉₂:pSTa₁₃’ fusion protein developed high titers of anti-LT and anti-STa antibodies. Furthermore, rabbit antiserum and antifecal antibodies were able to neutralize purified cholera toxin (CT) and STa toxin. In addition, preliminary data suggested that suckling piglets born from a sow immunized with the ‘pLT₁₉₂:pSTa₁₃’ fusion antigen were protected when challenged with a STa-positive ETEC. This study demonstrated that pSTa toxoids are antigenic when fused with a pLT toxoid, and elicited anti-LT and anti-STa antibodies were protective. This fusion strategy could provide instructive information to develop effective toxoid vaccines against ETEC associated diarrhea in animals and humans.