title: Detection of Antigenic Variants of Subtype H3 Swine Influenza A Viruses from Clinical Samples.
abstract: A large population of genetically and antigenically diverse influenza A viruses (IAVs) are circulating among the swine population, playing an important role in influenza ecology. Swine IAVs not only cause outbreaks among swine but also can be transmitted to humans, causing sporadic infections and even pandemic outbreaks. Antigenic characterizations of swine IAVs are key to understanding the natural history of these viruses in swine and to selecting strains for effective vaccines. However, influenza outbreaks generally spread rapidly among swine, and the conventional methods for antigenic characterization require virus propagation, a time-consuming process that can significantly reduce the effectiveness of vaccination programs. We developed and validated a rapid, sensitive, and robust method, the polyclonal serum-based proximity ligation assay (polyPLA), to identify antigenic variants of subtype H3N2 swine IAVs. This method utilizes oligonucleotide-conjugated polyclonal antibodies and quantifies antibody-antigen binding affinities by quantitative reverse transcription-PCR (RT-PCR). Results showed the assay can rapidly detect H3N2 IAVs directly from nasal wash or nasal swab samples collected from laboratory-challenged animals or during influenza surveillance at county fairs. In addition, polyPLA can accurately separate the viruses at two contemporary swine IAV antigenic clusters (H3N2 swine IAV-α and H3N2 swine IAV-ß) with a sensitivity of 84.9% and a specificity of 100.0%. The polyPLA can be routinely used in surveillance programs to detect antigenic variants of influenza viruses and to select vaccine strains for use in controlling and preventing disease in swine.
authors.affiliation: Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, USA.
authors.forename: Brigitte E
authors.initials: BE
authors.lastname: Martin
authors.affiliation: Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, USA.
authors.forename: Andrew S
authors.identifier: 0000-0002-0738-8453
authors.initials: AS
authors.lastname: Bowman
authors.affiliation: Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, USA.
authors.forename: Lei
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, USA.
authors.forename: Jacqueline M
authors.initials: JM
authors.lastname: Nolting
authors.affiliation: Department of Population Medicine and Pathobiology, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, USA.
authors.forename: David R
authors.initials: DR
authors.lastname: Smith
authors.affiliation: Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, USA.
authors.forename: Larry A
authors.initials: LA
authors.lastname: Hanson
authors.affiliation: Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, USA wan@cvm.msstate.edu.
authors.forename: Xiu-Feng
authors.initials: XF
authors.lastname: Wan
mesh_terms: D000818:Animals; D000940:Antigenic Variation; D000956:Antigens, Viral / Q000032:analysis*; D007118:Immunoassay / Q000379:methods*; D053122:Influenza A Virus, H3N2 Subtype / Q000145:classification* / Q000276:immunology / Q000302:isolation & purification; D009976:Orthomyxoviridae Infections / Q000662:veterinary* / Q000821:virology; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013552:Swine; D013553:Swine Diseases / Q000821:virology*; D014773:Virology / Q000379:methods*
chemical_list: D000956:Antigens, Viral
keywords: H3N2; antigenic drift; antigenic variation; approximate ligation assay; clinical sample; influenza A virus; polyPLA; serological assay; swine influenza virus; vaccine strain selection