title: The Epitope Recognized by Monoclonal Antibody 2B6 in the B/C Domains of Classical Swine Fever Virus Glycoprotein E2 Affects Viral Binding to Hyperimmune Sera and Replication.
abstract: Classical swine fever (CSF) is a highly contagious disease of pigs caused by CSF virus (CSFV). E2 is the major viral envelope protein of immune dominance that induces neutralizing antibodies and confers protection against CSFV infection. The B/C domains of E2 are variable among CSFV isolates, which could affect immunogenicity and binding to antibodies. We attempted to characterize the epitope recognized by a monoclonal antibody 2B6 (mAb-2B6) raised against the E2 B/C domains of the vaccine C-strain and to examine if mutations in the epitope region would affect antibody binding and viral neutralization. The epitope specific for mAb-2B6 recognition is linear, spanning five residues (774)DGXNP(778) in the B/C domains. The residue N777 is indispensable for the specificity. The epitope exists only in group 1 strains, but not in those of group 2. The recombinant viruses containing individual mutations on the epitope region lost the reactivity to mAb-2B6. The mutant virus RecC-N777S had low replication potential, about 10-fold decrease in the yield of progeny virus particles, whereas the mutant virus RecC-P778A reverted to proline upon continuous passaging. The mutations on the mAb-2B6 epitope region did not affect neutralization by anti-C-strain polyclonal sera from pigs. Deletion from aa774 covering the mAb-2B6 epitope, but not that from aa781, also affected binding with the polyclonal antibodies from vaccinated pigs, although the major binding region for the vaccinated antibodies is aa690-773.
authors.affiliation: Zhejiang University Institute of Preventive Veterinary Medicine, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Hangzhou 310058, P.R. China.
authors.forename: Chao
authors.initials: C
authors.lastname: Tong
authors.affiliation: Zhejiang University Institute of Preventive Veterinary Medicine, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Hangzhou 310058, P.R. China.
authors.forename: Ning
authors.initials: N
authors.lastname: Chen
authors.affiliation: Zhejiang University Institute of Preventive Veterinary Medicine, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Hangzhou 310058, P.R. China.
authors.forename: Xun
authors.initials: X
authors.lastname: Liao
authors.affiliation: Zhejiang University Institute of Preventive Veterinary Medicine, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Hangzhou 310058, P.R. China.
authors.forename: Wenqi
authors.initials: W
authors.lastname: Xie
authors.affiliation: Zhejiang University Institute of Preventive Veterinary Medicine, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Hangzhou 310058, P.R. China.
authors.forename: Dejiang
authors.initials: D
authors.lastname: Li
authors.affiliation: Zhejiang University Institute of Preventive Veterinary Medicine, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Hangzhou 310058, P.R. China.
authors.forename: Xiaoliang
authors.initials: X
authors.lastname: Li
authors.affiliation: Zhejiang University Institute of Preventive Veterinary Medicine, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Hangzhou 310058, P.R. China.
authors.forename: Weihuan
authors.initials: W
authors.lastname: Fang
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology* / Q000378:metabolism; D057134:Antibodies, Neutralizing / Q000276:immunology / Q000378:metabolism; D000914:Antibodies, Viral / Q000276:immunology* / Q000378:metabolism; D002460:Cell Line; D006692:Classical Swine Fever Virus / Q000502:physiology*; D018604:Epitope Mapping; D000939:Epitopes / Q000276:immunology* / Q000378:metabolism; D005838:Genotype; D009154:Mutation; D009500:Neutralization Tests; D011485:Protein Binding / Q000276:immunology; D054730:Protein Interaction Domains and Motifs / Q000276:immunology*; D013552:Swine; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D014779:Virus Replication
chemical_list: D000911:Antibodies, Monoclonal; D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D000939:Epitopes; D014759:Viral Envelope Proteins; C087086:glycoprotein E2, classical swine fever virus