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United States Department of Agriculture

Agricultural Research Service

Research Project: Antigenic Properties and Characterization of the Global Evolution of Influenza a Viruses (Iav) in Swine Project Number: 5030-32000-108-33
Project Type: Specific Cooperative Agreement

Start Date: Jun 01, 2014
End Date: Sep 30, 2018

Objective:
1. To utilize hemagglutination inhibition assays, antigenic cartography and other computational tools to quantify U.S. swine influenza antigenic evolution; and 2. the global relatedness of swine influenza viruses.

Approach:
Data from recent U.S. surveillance activities have indicated increased genetic diversity in swine influenza viruses (SIV) since the introduction of the H1N1pdm09 virus into the swine population. In addition, recent swine-to-human influenza transmission events in 2011-2012 of newly reassorted SIV (H3N2v) warrant intensive investigation into a better understanding of the evolution of swine viruses in the host population. Since nucleotide and amino acid sequences alone may not accurately define the antigenic cluster of the virus [a single amino acid change in the hemagglutinin (HA) protein can result in loss of protection] it is necessary to incorporate a quantification and visualization tool to study the antigenic phenotype of these viruses in order to predict population immunity in humans and pigs as well as implement effective control strategies. This work will build on the foundation of existing H1 and H3 swine serum panels generated at National Animal Disease Center (NADC), ARS. The previous work sets a baseline from which to measure ongoing evolution of contemporary swine and human isolates and quantifying the distance from current human seasonal or swine vaccine strains. Up to 6 contemporary IAV isolates (per year) selected based on frequency of isolation and genetic analysis data will be used for the production of reference antisera to be used for the hemagglutination-inhibition (HI) test. Priority will be given to emerging swine and/or isolates of public health concern for generation of antisera and as antigens to test against the serum panel. The NADC swine influenza antisera H1 and H3 panels, viruses, and sequences have been shared with a number of collaborators. We will continue to provide updated reagents to these collaborators and other CEIRS laboratories. Although many geographically restricted lineages of SIV exist, only H1N1, H1N2, and H3N2 are routinely endemic in swine. Many of these endemic SIV are the result of intercontinental spread of SIV or spillover of human seasonal influenza viruses. The use of a common set of sera that includes current human seasonal viruses will allow different continents and/or countries to standardize regional serology for a global understanding of the antigenic diversity in SIV. Serum panels generated at NADC will be distributed to collaborators in different countries such as in the Americas, Europe, and Asia to test cross-reactivity (by HI test) against SIV in these different geographical regions. Data generated will be combined and shared among collaborators. Viral antigens may be shared where permitted (due to import or shipping restrictions on border regulated animal diseases).

Last Modified: 10/20/2014
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