Genetic and antigenic characterization of influenza A virus circulating in Danish swine during the past decade

Kristina Fobian, Isa Kristina Kirk, Solvej Østergaard Breum, Nicola Lewis, Charlotte Kristiane Hjulsager, Lars Erik Larsen

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    Abstract

    Influenza A virus has been endemic in Danish swine for the last 30 years, with H1N1 and H1N2 being the dominating subtypes. The purpose of this study was to investigate the genetic and antigenic evolution of the influenza viruses found in Danish swine during the last 10 years. A total of 78 samples were isolated in MDCK cells, RNA extracted and the hemagglutinin and neuraminidase genes full length sequenced. In addition, the isolates were tested in hemagglutination inhibition (HI) tests against a panel of known antisera raised against a range of European swine influenza virus isolates. Phylogenetic analysis of the HA and NA genes revealed continuous evolutionary drift as expected for RNA viruses with low mutational selection pressure. Estimated selection pressures indicated that more purifying and less diversifying selection controlled the H1 evolution. The mean rates of synonymous and non-synonymous substitutions for H1, N1 and N2 were found to be in agreement with previously observed values for Eurasian swine lineages. Calculation of possible glycosylation sites in the hemagglutinin gene revealed that the H1N2 and H1N1 subtypes had three well conserved glycosylation sites in common. The results of the HI tests were analysed by antigenic cartography to quantify the antigenic relationship between the virus isolates. The antigenic cartography map showed that most of the Danish viruses were antigenic very similar, with only a few outliers. In conclusion, this study provided an important contribution to the complex epidemiology of circulating swine influenza virus in Denmark and indicates that vaccine development targeted against Danish H1N1 and H1N2 need only to include few components for the induction of cross protection against the predominant strains.

    The study was supported by grants from “European surveillance network for influenza in pigs (ESNIP) 3” (http://www.esnip3.eu) and The Danish Veterinary and Food Administration.
    Original languageEnglish
    Publication date2013
    Number of pages1
    Publication statusPublished - 2013
    EventInfluenza2013: One Influenza, One World, One Health - Oxford, United Kingdom
    Duration: 17 Sep 201319 Sep 2013
    http://lpmhealthcare.com/Influenza2013/influenzahome.htm

    Conference

    ConferenceInfluenza2013
    CountryUnited Kingdom
    CityOxford
    Period17/09/201319/09/2013
    Internet address

    Bibliographical note

    Podium presentation.

    Keywords

    • Swine influenza
    • Phylogeny
    • Antigenic cartography

    Cite this

    Fobian, K., Kirk, I. K., Breum, S. Ø., Lewis, N., Hjulsager, C. K., & Larsen, L. E. (2013). Genetic and antigenic characterization of influenza A virus circulating in Danish swine during the past decade. Abstract from Influenza2013, Oxford, United Kingdom.
    Fobian, Kristina ; Kirk, Isa Kristina ; Breum, Solvej Østergaard ; Lewis, Nicola ; Hjulsager, Charlotte Kristiane ; Larsen, Lars Erik. / Genetic and antigenic characterization of influenza A virus circulating in Danish swine during the past decade. Abstract from Influenza2013, Oxford, United Kingdom.1 p.
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    title = "Genetic and antigenic characterization of influenza A virus circulating in Danish swine during the past decade",
    abstract = "Influenza A virus has been endemic in Danish swine for the last 30 years, with H1N1 and H1N2 being the dominating subtypes. The purpose of this study was to investigate the genetic and antigenic evolution of the influenza viruses found in Danish swine during the last 10 years. A total of 78 samples were isolated in MDCK cells, RNA extracted and the hemagglutinin and neuraminidase genes full length sequenced. In addition, the isolates were tested in hemagglutination inhibition (HI) tests against a panel of known antisera raised against a range of European swine influenza virus isolates. Phylogenetic analysis of the HA and NA genes revealed continuous evolutionary drift as expected for RNA viruses with low mutational selection pressure. Estimated selection pressures indicated that more purifying and less diversifying selection controlled the H1 evolution. The mean rates of synonymous and non-synonymous substitutions for H1, N1 and N2 were found to be in agreement with previously observed values for Eurasian swine lineages. Calculation of possible glycosylation sites in the hemagglutinin gene revealed that the H1N2 and H1N1 subtypes had three well conserved glycosylation sites in common. The results of the HI tests were analysed by antigenic cartography to quantify the antigenic relationship between the virus isolates. The antigenic cartography map showed that most of the Danish viruses were antigenic very similar, with only a few outliers. In conclusion, this study provided an important contribution to the complex epidemiology of circulating swine influenza virus in Denmark and indicates that vaccine development targeted against Danish H1N1 and H1N2 need only to include few components for the induction of cross protection against the predominant strains.The study was supported by grants from “European surveillance network for influenza in pigs (ESNIP) 3” (http://www.esnip3.eu) and The Danish Veterinary and Food Administration.",
    keywords = "Swine influenza, Phylogeny, Antigenic cartography",
    author = "Kristina Fobian and Kirk, {Isa Kristina} and Breum, {Solvej {\O}stergaard} and Nicola Lewis and Hjulsager, {Charlotte Kristiane} and Larsen, {Lars Erik}",
    note = "Podium presentation.; Influenza2013 : One Influenza, One World, One Health ; Conference date: 17-09-2013 Through 19-09-2013",
    year = "2013",
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    Fobian, K, Kirk, IK, Breum, SØ, Lewis, N, Hjulsager, CK & Larsen, LE 2013, 'Genetic and antigenic characterization of influenza A virus circulating in Danish swine during the past decade' Influenza2013, Oxford, United Kingdom, 17/09/2013 - 19/09/2013, .

    Genetic and antigenic characterization of influenza A virus circulating in Danish swine during the past decade. / Fobian, Kristina; Kirk, Isa Kristina; Breum, Solvej Østergaard; Lewis, Nicola; Hjulsager, Charlotte Kristiane; Larsen, Lars Erik.

    2013. Abstract from Influenza2013, Oxford, United Kingdom.

    Research output: Contribution to conferenceConference abstract for conferenceResearchpeer-review

    TY - ABST

    T1 - Genetic and antigenic characterization of influenza A virus circulating in Danish swine during the past decade

    AU - Fobian, Kristina

    AU - Kirk, Isa Kristina

    AU - Breum, Solvej Østergaard

    AU - Lewis, Nicola

    AU - Hjulsager, Charlotte Kristiane

    AU - Larsen, Lars Erik

    N1 - Podium presentation.

    PY - 2013

    Y1 - 2013

    N2 - Influenza A virus has been endemic in Danish swine for the last 30 years, with H1N1 and H1N2 being the dominating subtypes. The purpose of this study was to investigate the genetic and antigenic evolution of the influenza viruses found in Danish swine during the last 10 years. A total of 78 samples were isolated in MDCK cells, RNA extracted and the hemagglutinin and neuraminidase genes full length sequenced. In addition, the isolates were tested in hemagglutination inhibition (HI) tests against a panel of known antisera raised against a range of European swine influenza virus isolates. Phylogenetic analysis of the HA and NA genes revealed continuous evolutionary drift as expected for RNA viruses with low mutational selection pressure. Estimated selection pressures indicated that more purifying and less diversifying selection controlled the H1 evolution. The mean rates of synonymous and non-synonymous substitutions for H1, N1 and N2 were found to be in agreement with previously observed values for Eurasian swine lineages. Calculation of possible glycosylation sites in the hemagglutinin gene revealed that the H1N2 and H1N1 subtypes had three well conserved glycosylation sites in common. The results of the HI tests were analysed by antigenic cartography to quantify the antigenic relationship between the virus isolates. The antigenic cartography map showed that most of the Danish viruses were antigenic very similar, with only a few outliers. In conclusion, this study provided an important contribution to the complex epidemiology of circulating swine influenza virus in Denmark and indicates that vaccine development targeted against Danish H1N1 and H1N2 need only to include few components for the induction of cross protection against the predominant strains.The study was supported by grants from “European surveillance network for influenza in pigs (ESNIP) 3” (http://www.esnip3.eu) and The Danish Veterinary and Food Administration.

    AB - Influenza A virus has been endemic in Danish swine for the last 30 years, with H1N1 and H1N2 being the dominating subtypes. The purpose of this study was to investigate the genetic and antigenic evolution of the influenza viruses found in Danish swine during the last 10 years. A total of 78 samples were isolated in MDCK cells, RNA extracted and the hemagglutinin and neuraminidase genes full length sequenced. In addition, the isolates were tested in hemagglutination inhibition (HI) tests against a panel of known antisera raised against a range of European swine influenza virus isolates. Phylogenetic analysis of the HA and NA genes revealed continuous evolutionary drift as expected for RNA viruses with low mutational selection pressure. Estimated selection pressures indicated that more purifying and less diversifying selection controlled the H1 evolution. The mean rates of synonymous and non-synonymous substitutions for H1, N1 and N2 were found to be in agreement with previously observed values for Eurasian swine lineages. Calculation of possible glycosylation sites in the hemagglutinin gene revealed that the H1N2 and H1N1 subtypes had three well conserved glycosylation sites in common. The results of the HI tests were analysed by antigenic cartography to quantify the antigenic relationship between the virus isolates. The antigenic cartography map showed that most of the Danish viruses were antigenic very similar, with only a few outliers. In conclusion, this study provided an important contribution to the complex epidemiology of circulating swine influenza virus in Denmark and indicates that vaccine development targeted against Danish H1N1 and H1N2 need only to include few components for the induction of cross protection against the predominant strains.The study was supported by grants from “European surveillance network for influenza in pigs (ESNIP) 3” (http://www.esnip3.eu) and The Danish Veterinary and Food Administration.

    KW - Swine influenza

    KW - Phylogeny

    KW - Antigenic cartography

    M3 - Conference abstract for conference

    ER -

    Fobian K, Kirk IK, Breum SØ, Lewis N, Hjulsager CK, Larsen LE. Genetic and antigenic characterization of influenza A virus circulating in Danish swine during the past decade. 2013. Abstract from Influenza2013, Oxford, United Kingdom.