title: S1 domain of the porcine epidemic diarrhea virus spike protein as a vaccine antigen.
abstract: BACKGROUND
  Porcine epidemic diarrhea virus (PEDV) is a highly contagious virus infecting pigs of all ages with high morbidity and mortality among newborn piglets. Currently, there is no effective vaccine available to protect the pigs from PEDV. The N-terminal subunit of spike protein (S1) is responsible for virus binding to the cellular receptor and contains a number of neutralizing antibody epitopes. Thus, we expressed and produced recombinant S1 protein to protect newborn piglets by immunization of sows.
  
  
  METHODS
  Affinity tagged PEDV S1 protein was expressed in a secretory form in yeast, insect and mammalian cells to identify the most suitable production system. Purified recombinant protein was analysed by SDS-PAGE, Western blot and deglycosylation assay. A pregnant sow was intramuscularly immunized three times with adjuvanted recombinant protein prior to farrowing. PEDV-specific immune responses in sera and colostrum of the sow and piglets were assayed by ELISA and virus neutralization assays. Piglets were challenged orally with PEDV, and clinical parameters were monitored for 6 days post-challenge.
  
  
  CONCLUSIONS
  Of three eukaryotic expression systems tested (yeast, insect-cell, and mammalian), expression by HEK-293 T cells gave the highest yield of protein that was N-glycosylated and was the most appropriate candidate for vaccination. Administration of the subunit vaccine in a sow resulted in induction of S1-specific IgG and IgA that were passively transferred to the suckling piglets. Also, high virus neutralization titres were observed in the serum of the vaccinated sow and its piglets. After PEDV challenge, piglets born to the vaccinated sow exhibited less severe signs of disease and significantly lower mortality compared to the piglets of a control sow. However, there were no significant differences in diarrhea, body weight and virus shedding. Thus, vaccination with S1 subunit vaccine failed to provide complete protection to suckling piglets after challenge exposure, and further improvements are needed for the development of a subunit vaccine that fully protects against PEDV infection.
authors.affiliation: Vaccine and Infectious Disease Organization - International Vaccine Center (VIDO-InterVac), University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK, S7N 5E3, Canada.
authors.forename: Niraj
authors.initials: N
authors.lastname: Makadiya
authors.affiliation: Vaccine and Infectious Disease Organization - International Vaccine Center (VIDO-InterVac), University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK, S7N 5E3, Canada.
authors.forename: Robert
authors.initials: R
authors.lastname: Brownlie
authors.affiliation: Vaccine and Infectious Disease Organization - International Vaccine Center (VIDO-InterVac), University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK, S7N 5E3, Canada.
authors.forename: Jan
authors.initials: J
authors.lastname: van den Hurk
authors.affiliation: Vaccine and Infectious Disease Organization - International Vaccine Center (VIDO-InterVac), University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK, S7N 5E3, Canada.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Berube
authors.affiliation: Vaccine and Infectious Disease Organization - International Vaccine Center (VIDO-InterVac), University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK, S7N 5E3, Canada.
authors.forename: Brenda
authors.initials: B
authors.lastname: Allan
authors.affiliation: Vaccine and Infectious Disease Organization - International Vaccine Center (VIDO-InterVac), University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK, S7N 5E3, Canada.
authors.forename: Volker
authors.initials: V
authors.lastname: Gerdts
authors.affiliation: Vaccine and Infectious Disease Organization - International Vaccine Center (VIDO-InterVac), University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK, S7N 5E3, Canada. alex.zak@usask.ca.
authors.forename: Alexander
authors.initials: A
authors.lastname: Zakhartchouk
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage; D000818:Animals; D057134:Antibodies, Neutralizing / Q000032:analysis; D000914:Antibodies, Viral / Q000032:analysis; D000956:Antigens, Viral / Q000235:genetics / Q000276:immunology*; D003126:Colostrum / Q000276:immunology; D018352:Coronavirus Infections / Q000473:pathology / Q000517:prevention & control / Q000662:veterinary*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D007273:Injections, Intramuscular; D009500:Neutralization Tests; D053485:Porcine epidemic diarrhea virus / Q000235:genetics / Q000276:immunology*; D011247:Pregnancy; D044967:Serum / Q000276:immunology; D064370:Spike Glycoprotein, Coronavirus / Q000235:genetics / Q000276:immunology*; D013552:Swine; D016896:Treatment Outcome; D022223:Vaccines, Subunit / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D014765:Viral Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*
chemical_list: D000276:Adjuvants, Immunologic; D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D000956:Antigens, Viral; D064370:Spike Glycoprotein, Coronavirus; D022223:Vaccines, Subunit; D014614:Vaccines, Synthetic; D014765:Viral Vaccines
keywords: Lactogenic immunity; PEDV; S1; Subunit vaccine