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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Virus and Prion Research » Research » Publications at this Location » Publication #400126
Research Project: Intervention Strategies to Control Endemic and New and Emerging Influenza A Virus Infections in Swine

Location: Virus and Prion Research

Title: Divergent pathology between highly pathogenic avian influenza A (H5N1) strains in swine

Author
item Arruda, Bailey
item Buckley, Alexandra
item KILLIAN, MARY - Diagnostic Virology Laboratory/ National Veterinary Services Laboratories
item HINES BERGESON, NICHOLE - Diagnostic Virology Laboratory/ National Veterinary Services Laboratories
item TORACHETTI, MIA - Diagnostic Virology Laboratory/ National Veterinary Services Laboratories
item Baker, Amy

Submitted to: American Association of Swine Veterinarians Annual Meeting
Publication Type: Proceedings
Publication Acceptance Date: 1/13/2023
Publication Date: 3/4/2023
Citation: Arruda, B.L., Devries, A.C., Killian, M., Hines Bergeson, N., Torachetti, M., Baker, A.L. 2023. Divergent pathology between highly pathogenic avian influenza A (H5N1) strains in swine. American Association of Swine Veterinarians Annual Meeting. American Association of Swine Veterinarians Annual Meeting, March 4-7, 2023, Aurora, Colorado.

Interpretive Summary: Highly pathogenic avian influenza (HPAI) viruses pose substantial risk to poultry due to their negative agroeconomic impact and pandemic potential. Influenza A viruses (IAV) occasionally cross species barriers, including H5 avian influenza viruses. Assessing the risk of H5N1 strains from the current outbreak as a potential for infecting pigs is necessary due to its wide distribution in states with high populations of pigs and the potential for reassortment with endemic swine adapted influenza A viruses. We evaluated two strains of the 2022 spring HPAI H5N1 outbreak in swine. Neither HPAI H5N1 strain was detected in the upper respiratory tract nor transmitted to contact pigs; however, viral replication in the lower respiratory tract, lesions and antigen labeling differed between strains. Future studies are needed to identify determinants of HPAI pathogenicity, virulence, and transmissibility in swine to inform early warning systems. The risk of reassortment with endemic swine IAV is a consideration; however, the risk is low in confinement operations with industry standard biosecurity. Bird proofing feed and facilities and not using untreated surface or well water that may be contaminated with wild waterfowl feces would be prudent to further reduce this risk.

Technical Abstract: Highly pathogenic avian influenza (HPAI) viruses pose substantial risk to poultry due to their negative agroeconomic impact and pandemic potential. Influenza A viruses occasionally cross species barriers, including H5 avian influenza viruses. Since February 2022, H5N1 HPAI belonging to the goose/Guangdong 2.3.4.4b hemagglutinin (HA) phylogenetic clade from a trans-Atlantic incursion caused outbreaks across the North American continent. Assessing the risk of 2.3.4.4b H5N1 strains from the current outbreak as a potential for infecting pigs is necessary due to its wide distribution in states with high populations of pigs and the potential for reassortment with endemic swine adapted IAV. We evaluated two strains of the 2022 spring HPAI H5N1 2.3.4.4b clade outbreak, A/turkey/Minnesota/22-010654-002/2022 (A/turkey/MN/22) and A/bald eagle/Florida/22-006544-004/2022 (A/bald eagle/FL/22) in a swine inoculation model. These two strains resulted from Eurasian avian HPAI 2.3.4.4b H5N1 reassortment with North American low pathogenic AIV lineage internal genes and represented two different reassortment patterns frequently detected among H5N1 strains during the spring of 2022. Neither HPAI H5N1 strain was detected in the upper respiratory tract nor transmitted to contact pigs; however, viral replication in the lower respiratory tract, lesions and antigen labeling differed between strains. Future studies are needed to identify determinants of HPAI pathogenicity, virulence, and transmissibility in swine to inform early warning systems. The risk of reassortment with endemic swine IAV is a consideration; however, the risk is low in confinement operations with industry standard biosecurity. Bird proofing feed and facilities and not using untreated surface or well water that may be contaminated with wild waterfowl feces would be prudent to further reduce this risk.