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United States Department of Agriculture

Agricultural Research Service

Research Project: Antigenic Relatedness of Influenza a Viruses and Use of Antigenic Cartography in Vaccine Strain Selection for Swine Project Number: 3625-32000-108-09
Project Type: Specific Cooperative Agreement

Start Date: Jun 01, 2012
End Date: Sep 30, 2014

Objective:
1. Utilize cross-hemagglutination inhibition (HI) assays and antigenic cartography to determine the antigenic relatedness among U.S. swine isolates and between swine isolates from other regions and influenza A viruses from other host species. 2. Determine if antigenic cartography is a predictor of cross-protection for vaccine strain selection in swine.

Approach:
Characterization of influenza A viruses (IAV) circulating in pigs and other non-human mammals has been chronically underfunded and virtually nonexistent in many areas of the world. Antigenic characterization is critical for understanding the evolution of IAV in swine as well as the effectiveness of diagnostic serologic assays and vaccines. Antigenic cartography is a computational tool which calculates antigenic distances between all pairs of viruses and anti-sera included in the HI analysis and plots the distances in a 2- or 3-dimensional grid. Antigenic distances measured in the HI assay and visualized by antigenic cartography with pig hyper-immune sera will be compared to antigenic distance measurements from other types of anti-sera such as convalescent swine sera, ferret sera, or other potential reference sera. The antigenic distances will be used to monitor antigenic evolution or drift in viruses from the U.S. and worldwide as part of ARS-NADC in-house objectives as well as a member of the OFFLU global SIV network. If the swine hyper-immune sera immunologically characterizes the antigenic differences between strains in a similar manner to comparitive reference sera, we will use the hyper-immune sera to quantify the antigenic relationships among swine influenza virus strains in the US and worldwide relative to vaccine strains using HI paired with antigenic cartography. Viruses will be selected based on their antigenic distances in the antigenic map for evaluation in experimental vaccines in in vivo efficacy and cross-protection studies to be conducted at NADC.

Last Modified: 7/22/2014
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