title: Immunogenicity and antigenic relationships among spike proteins of porcine epidemic diarrhea virus subtypes G1 and G2.
abstract: Porcine epidemic diarrhea virus (PEDV) is a coronavirus that infects cells lining the small intestine of swine, resulting in vomiting, diarrhea, and dehydration. The amino acid sequence of the spike (S) protein, which is the principal target recognized by host immune cells, has multiple mutations that distinguish the two PEDV genotypes, G1 and G2. To determine whether these mutations lead to changes in antigenicity, as suggested by the failure of PEDV vaccines in China, we first optimized the codons of typical S genes of the CV777 vaccine strain (G1 subtype) and LNCT2 strain (G2 subtype) and expressed the recombinant full-length sequence of the S protein in a eukaryotic expression system. The IgG antibody levels of serum from mice immunized with purified S protein were markedly high. Antigenicity was compared by detection of polyclonal antibodies (PAbs) against the virus and S protein using an enzyme-linked immunosorbent assay (ELISA), an indirect immunofluorescence assay (IFA), and a serum cross-neutralization (SN) assay. Reactivity with the PAbs revealed significant cross-reactivity between the two PEDV subtypes, although there was a twofold difference in the antigenic responses based on PAb titers in the ELISA and IFA. Consistent with the variation in the S gene sequences, the SN titer suggested differences in the neutralization activity of the S protein between the two subtypes, which could explain the antigenic variation between the PEDV subtypes G1 and G2.
authors.affiliation: Division of Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, 150001, People's Republic of China.
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Wang
authors.affiliation: Division of Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, 150001, People's Republic of China.
authors.forename: Jianfei
authors.initials: J
authors.lastname: Chen
authors.affiliation: Division of Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, 150001, People's Republic of China.
authors.forename: Da
authors.initials: D
authors.lastname: Shi
authors.affiliation: Division of Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, 150001, People's Republic of China.
authors.forename: Hongyan
authors.initials: H
authors.lastname: Shi
authors.affiliation: Division of Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, 150001, People's Republic of China.
authors.forename: Xin
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Division of Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, 150001, People's Republic of China.
authors.forename: Jing
authors.initials: J
authors.lastname: Yuan
authors.affiliation: Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Shanghai Public Health Clinical Center and Shanghai Medical College, Fudan University, Shanghai, 200032, People's Republic of China.
authors.forename: Shibo
authors.initials: S
authors.lastname: Jiang
authors.affiliation: Division of Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, 150001, People's Republic of China. fl@hvri.ac.cn.
authors.forename: Li
authors.initials: L
authors.lastname: Feng
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D000956:Antigens, Viral / Q000235:genetics / Q000276:immunology*; D002681:China; D004797:Enzyme-Linked Immunosorbent Assay; D019084:Fluorescent Antibody Technique, Indirect; D005838:Genotype; D007114:Immunization; D007074:Immunoglobulin G / Q000097:blood; D051379:Mice; D009500:Neutralization Tests; D053485:Porcine epidemic diarrhea virus / Q000145:classification / Q000235:genetics / Q000276:immunology*; D064370:Spike Glycoprotein, Coronavirus / Q000235:genetics / Q000276:immunology*
chemical_list: D000914:Antibodies, Viral; D000956:Antigens, Viral; D007074:Immunoglobulin G; D064370:Spike Glycoprotein, Coronavirus