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United States Department of Agriculture

Agricultural Research Service

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Research Project: Antigenic Properties and Characterization of the Global Evolution of Influenza A Viruses (IAV) in Swine

Location: Virus and Prion Research

Project Number: 5030-32000-108-32-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Jun 1, 2014
End Date: Sep 23, 2014

To utilize influenza A virus (IAV) hemagglutinin (HA) gene sequences from the U.S. and globally to develop a cluster designation web-based tool and to define criteria for a cluster nomenclature system. The global relatedness of the HA genes will be investigated at the genetic and antigenic levels.

Data from recent U.S. and global 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, multiple human-to-swine transmission events warrant intensive investigation into a better understanding of the evolution of swine viruses in the host population and a common nomenclature system with defined criteria that will have utility at the global level. The objective of this new nomenclature system developed and proposed by the OFFLU Swine Influenza Virus group is to create a common language to be used by animal and human health sectors to designate swine influenza viruses on a global scale. This system will allow for viruses around the world to be evaluated by a unified set of criteria and their genetic relationships understood in a common context. Such a system is also important for targeting groups of viruses to study for antigenic properties and developing effective vaccines. The proposed system is a phylogenetic classification system, distinguishing clusters of viruses that share common genetic characteristics. Therefore, it defines the relationship between the different influenza strains, which are continually evolving. This system enables the assessment of the genetic relationships between influenza viruses circulating in swine among different geographic regions as well as between swine and human seasonal influenza viruses. The classification is based on the gene encoding the hemagglutinin (HA) protein, which plays a key role in virus-host interactions and in vaccine strain selection. The criteria were adapted from a previous initiative to describe avian influenza H5 genetic diversity to be applicable to a global influenza A virus genetic dataset from swine and humans. The group will continue to work with the Influenza Research Database ( to provide the HA gene cluster names based on the new system for future web-based cluster determination tools for swine HA sequences with free public access.

Last Modified: 10/19/2017
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