title: Prediction and characterization of novel epitopes of serotype A foot-and-mouth disease viruses circulating in East Africa using site-directed mutagenesis.
abstract: Epitopes on the surface of the foot-and-mouth disease virus (FMDV) capsid have been identified by monoclonal antibody (mAb) escape mutant studies leading to the designation of four antigenic sites in serotype A FMDV. Previous work focused on viruses isolated mainly from Asia, Europe and Latin America. In this study we report on the prediction of epitopes in African serotype A FMDVs and testing of selected epitopes using reverse genetics. Twenty-four capsid amino acid residues were predicted to be of antigenic significance by analysing the capsid sequences (n = 56) using in silico methods, and six residues by correlating capsid sequence with serum-virus neutralization data. The predicted residues were distributed on the surface-exposed capsid regions, VP1-VP3. The significance of residue changes at eight of the predicted epitopes was tested by site-directed mutagenesis using a cDNA clone resulting in the generation of 12 mutant viruses involving seven sites. The effect of the amino acid substitutions on the antigenic nature of the virus was assessed by virus neutralization (VN) test. Mutations at four different positions, namely VP1-43, VP1-45, VP2-191 and VP3-132, led to significant reduction in VN titre (P value = 0.05, 0.05, 0.001 and 0.05, respectively). This is the first time, to our knowledge, that the antigenic regions encompassing amino acids VP1-43 to -45 (equivalent to antigenic site 3 in serotype O), VP2-191 and VP3-132 have been predicted as epitopes and evaluated serologically for serotype A FMDVs. This identifies novel capsid epitopes of recently circulating serotype A FMDVs in East Africa.
authors.affiliation: The Pirbright Institute, Ash Road, Woking, Surrey, GU24 0NF, UK.
authors.forename: Fufa Dawo
authors.initials: FD
authors.lastname: Bari
authors.affiliation: The Pirbright Institute, Ash Road, Woking, Surrey, GU24 0NF, UK.
authors.forename: Satya
authors.initials: S
authors.lastname: Parida
authors.affiliation: The Pirbright Institute, Ash Road, Woking, Surrey, GU24 0NF, UK.
authors.forename: Amin S
authors.initials: AS
authors.lastname: Asfor
authors.affiliation: Boyd Orr Centre for Population and Ecosystem Health, Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, G12 8QQ, UK.
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Haydon
authors.affiliation: Boyd Orr Centre for Population and Ecosystem Health, Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, G12 8QQ, UK.|The Pirbright Institute, Ash Road, Woking, Surrey, GU24 0NF, UK.
authors.forename: Richard
authors.initials: R
authors.lastname: Reeve
authors.affiliation: The Pirbright Institute, Ash Road, Woking, Surrey, GU24 0NF, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Paton
authors.affiliation: The Pirbright Institute, Ash Road, Woking, Surrey, GU24 0NF, UK.
authors.forename: Mana
authors.initials: M
authors.lastname: Mahapatra
mesh_terms: D000351:Africa, Eastern; D000818:Animals; D057134:Antibodies, Neutralizing / Q000276:immunology; D000914:Antibodies, Viral / Q000276:immunology; D036022:Capsid Proteins / Q000235:genetics / Q000276:immunology*; D002460:Cell Line; D000939:Epitopes / Q000235:genetics / Q000276:immunology*; D029544:Foot-and-Mouth Disease Virus / Q000235:genetics / Q000276:immunology*; D016297:Mutagenesis, Site-Directed; D009500:Neutralization Tests; D059386:Reverse Genetics; D065288:Serogroup
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D036022:Capsid Proteins; D000939:Epitopes