A continuous epitope from transmissible gastroenteritis virus S protein fused to E. coli heat-labile toxin B subunit expressed by attenuated Salmonella induces serum and secretory immunity

Cristian Smerdou, Ines M. Anton, Juan Plana, Roy Curtiss, Luis Enjuanes

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Antigenic site D from the spike protein of transmissible gastroenteritis virus (TGEV), which is a continuous epitope critical in neutralization, has been expressed as a fusion protein with E. coli heat-labile toxin B subunit (LT-B) in attenuated S. typhimurium. Synthetic peptides containing the sequence of site D induced TGEV neutralizing antibodies when inoculated subcutaneously in both rabbits and swine. A synthetic oligonucleotide encoding residues 373-398 of TGEV S protein, including antigenic site D, was cloned in frame with the 3' end of LT-B gene, into a plasmid used to transform S. typhimurium Δasd (χ)3730 A collection of 6 recombinant plasmids designated pYALTB-D I-VI encoding LTB-site D fusions with a variable number of site D sequences were selected. Four of the 6 LTB-site D fusion products expressed in S. typhimurium (χ)3730 formed oligomers (pentamers) that dissociated at >70°. S. typhimurium (χ)3730 (pYALTB-D) V and VI expressed the oligomer forming products with higher antigenicity. Partially purified LTB-site D fusion product expressed from S. typhimurium (χ)3730 (pYALTB-D) V induced anti-TGEV neutralizing antibodies in rabbits. Recombinant vaccine strain S. typhimurium Δcya Δcrp Δasd (χ)3987 transformed with plasmid pYALTB-D V expressed constitutively products; that formed oligomers presumably containing 20 copies of site D, and showed a high stability in vitro. This recombinant strain was orally inoculated in rabbits and induced TGEV specific antibodies in both serum and intestinal secretion.

Original languageEnglish (US)
Pages (from-to)1-9
Number of pages9
JournalVirus research
Issue number1
StatePublished - Mar 1996



  • Coronavirus
  • Mucosal immunity
  • Salmonella typhimurium
  • TGEV
  • Transmissible gastroenteritis virus

ASJC Scopus subject areas

  • Cancer Research
  • Virology
  • Infectious Diseases

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