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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Virus and Prion Research » Research » Research Project #431407

Research Project: Mechanisms of Swine Influenza A Virus Evolution

Location: Virus and Prion Research

Project Number: 5030-32000-120-11-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Sep 20, 2016
End Date: Sep 19, 2019

Objective:
Define the molecular basis for evolution of hemagglutinin (HA) and neuraminidase (NA) proteins in circulating swine influenza A virus (IAV).

Approach:
This objective will be met by 1) Evaluating contemporary H3 HA and N2 NA evolution through site directed mutagenesis and reverse genetics, and 2) Investigating the phenotypic impact of genetic changes to HA and NA. Previous work in site directed mutagenesis showed that amino acid substitutions at one or more of six key sites (antigenic motif) had major impacts on antigenic variation. Since then, additional antigenic motifs have been found in wild type circulating H3 IAV that were not previously tested. Additional site directed mutants will be generated to match newly identified antigenic motifs. The effect of these substitutions will be evaluated in serologic assays combined with antigenic cartography and by in vitro and in vivo studies. Additionally, several lineages of NA genes co-circulate in U.S. swine. Reverse engineering will be used to construct relevant neuraminidase inhibition assay antigens to test the antigenic impact in serologic assays. Thirdly, novel human-like H3 reassortant viruses were identified in swine in 2014 and their genetic make are unique compositions, including a hemagglutinin (HA) gene. Reverse genetics will be used to identify the genetic components that confer fitness to swine and/or ferrets. The wild type and reverse genetics derived viruses will be assessed for pathogenicity and transmission properties in swine at the ARS and in ferrets as a risk assessment model for human public health at Cooperator's facility.