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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Virus and Prion Research » Research » Publications at this Location » Publication #349421
Research Project: Intervention Strategies to Control Influenza A Virus Infection in Swine

Location: Virus and Prion Research

Title: Pathogenesis and transmission in the swine host of influenza A viruses with dominant H1 genome constellations found in U.S. swine herds

Author
item SOUZA, CARINE - Orise Fellow
item Anderson, Tavis
item KAPLAN, BRYAN - Orise Fellow
item GAUGER, PHILLIP - Iowa State University
item Abente, Eugenio
item Baker, Amy

Submitted to: International Symposium on Neglected Influenza Viruses
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/2018
Publication Date: 4/18/2018
Citation: Souza, C.K., Anderson, T.K., Kaplan, B.S., Gauger, P.C., Abente, E.J., Vincent, A.L. 2018. Pathogenesis and transmission in the swine host of influenza A viruses with dominant H1 genome constellations found in U.S. swine herds [abstract]. International Symposium on Neglected Influenza Viruses. Abstract No.O10.

Interpretive Summary:

Technical Abstract: Influenza A viruses (IAV) are an economic and health burden to the swine industry and have a major public health importance. There is substantial IAV genetic diversity in pigs in the US, including distinct H1 phylogenetic clades such as 1A.1 (alpha), 1A.2 (beta), 1B.2.2.1 (delta-1a), 1B.2.2.2 (delta-1b), 1B.2.1 (delta-2), 1A.3.3.2 (pandemic) and 1A.3.3.3 (gamma). Detections of reassorted IAV in swine remains high after repeated introductions of H1N1pdm09 from humans into pig populations. A previous study identified dynamic patterns among whole-genome constellations of H1N1 and H1N2 in US pig herds from 2009 to 2016. The dominant gene constellation patterns were assigned as H1 clade, NA lineage (classical, 1998 or 2002) and internal gene lineage (TRIG - T or Pandemic – P) in the order of PB2, PB1, PA, NP, M and NS. This work demonstrated that the most abundant H1 genome patterns were gamma/N1-TTPPPT, delta-1a/N2-2002-TTTTPT, delta-1b/N2-2002-TTTPPT, delta-2/N2-1998-TTTTPT and alpha/N2-2002-TTPTPT. To understand the clinical outcome of viruses with these dominant genome constellations, we assessed the pathogenesis and transmission of 5 IAV isolates from swine. The gamma/N1-TTPPPT demonstrated a significantly higher percentage of lung lesions compared to the negative control and delta-1b/N2-2002-TTTPPT groups. All primary infected pigs shed virus between 1 to 5 days post infection, with subtle differences between group mean titers on different days. All viruses replicated to high titers in the lungs, and all pigs in the contact groups had detectable virus titers by 5 days post contact. Although the gamma/N1-TTPPPT presented more severe lung lesions, shedding and transmission was comparable to the other viruses. These results indicate that viruses with these dominant HA/NA clades and genome constellations were virulent and replicated efficiently, despite containing different internal gene patterns. Additionally, the gamma/N1-TTPPPT can serve as a tool to identify the molecular determinants of pathogenesis/virulence. Further work is required to compare these viruses with others containing genome constellations that are less frequently, but persistently, detected and viruses with genome constellations that have had decreased detection frequency over time and understand what role the genome constellation plays in the clinical/infectious phenotype of IAV.