title: Comparative virulence of wild-type H1N1pdm09 influenza A isolates in swine.
abstract: In 2009, a novel swine-origin H1N1 (H1N1pdm09) influenza A virus (IAV) reached pandemic status and was soon after detected in pigs worldwide. The objective of this study was to evaluate whether differences in the HA protein can affect pathogenicity and antigenicity of H1N1pdm09 in swine. We compared lung pathology, viral replication and shedding and the antigenic relationships of four wild-type H1N1pdm09 viruses in pigs: one human (CA/09) and three isolated in swine after the pandemic (IL/09, IL/10, and MN/10). The swine strains were selected based upon unique amino acid substitutions in the HA protein. All selected viruses resulted in mild disease and viral shedding through nasal and oral fluids, however, viral replication and the degree of pathology varied between the isolates. A/Swine/IL/5265/2010 (IL/10), with substitutions I120M, S146G, S186P, V252M, had lower viral titers in the lungs and nasal secretions and fewer lung lesions. The other two swine viruses caused respiratory pathology and replicated to titers similar to the human CA/09, although MN/10 (with mutations D45Y, K304E, A425S) had lower nasal shedding. Swine-adapted H1N1pdm09 have zoonotic potential, and have reassorted with other co-circulating swine viruses, influencing the evolution of IAV in swine globally. Further, our results suggest that amino acid changes in the HA gene have the potential to alter the virulence of H1N1pdm09 in swine. Importantly, the limited clinical signs in pigs could result in continued circulation of these viruses with other endemic swine IAVs providing opportunities for reassortment.
authors.affiliation: Virus and Prion Research Unit, National Animal Disease Center, USDA, Agricultural Research Service, 1920 Dayton Avenue, Ames, IA 50010, USA; Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, K-221 Mosier Hall, Manhattan, KS 66506, USA.
authors.forename: Jamie N
authors.initials: JN
authors.lastname: Henningson
authors.affiliation: Virus and Prion Research Unit, National Animal Disease Center, USDA, Agricultural Research Service, 1920 Dayton Avenue, Ames, IA 50010, USA.
authors.forename: Daniela S
authors.initials: DS
authors.lastname: Rajao
authors.affiliation: Virus and Prion Research Unit, National Animal Disease Center, USDA, Agricultural Research Service, 1920 Dayton Avenue, Ames, IA 50010, USA.
authors.forename: Pravina
authors.initials: P
authors.lastname: Kitikoon
authors.affiliation: Istituto Zooprofilattico Sperimentale dell'Abruzzo e Molise "G. Caporale", Teramo, Italy.
authors.forename: Alessio
authors.initials: A
authors.lastname: Lorusso
authors.affiliation: University of Minnesota Veterinary Diagnostic Laboratory, 1333 Gortner Avenue, St. Paul, MN 55108, USA.
authors.forename: Marie R
authors.initials: MR
authors.lastname: Culhane
authors.affiliation: Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.
authors.forename: Nicola S
authors.initials: NS
authors.lastname: Lewis
authors.affiliation: Virus and Prion Research Unit, National Animal Disease Center, USDA, Agricultural Research Service, 1920 Dayton Avenue, Ames, IA 50010, USA; Department of Biology, Georgia Southern University, P.O. Box 8042-1, Statesboro, GA 30460, USA.
authors.forename: Tavis K
authors.initials: TK
authors.lastname: Anderson
authors.affiliation: Virus and Prion Research Unit, National Animal Disease Center, USDA, Agricultural Research Service, 1920 Dayton Avenue, Ames, IA 50010, USA. Electronic address: amy.vincent@ars.usda.gov.
authors.forename: Amy L
authors.initials: AL
authors.lastname: Vincent
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D003429:Cross Reactions; D006389:Hemagglutinins, Viral / Q000235:genetics*; D053118:Influenza A Virus, H1N1 Subtype / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity* / Q000502:physiology; D008168:Lung / Q000473:pathology; D009976:Orthomyxoviridae Infections / Q000473:pathology / Q000662:veterinary* / Q000821:virology; D013552:Swine; D013553:Swine Diseases / Q000473:pathology / Q000821:virology*; D014774:Virulence; D014779:Virus Replication; D017201:Virus Shedding
chemical_list: D006389:Hemagglutinins, Viral
keywords: Cross-reactivity; HI; Influenza A virus; Pandemic; Pathology; Swine