title: Polymorphisms in the haemagglutinin gene influenced the viral shedding of pandemic 2009 influenza virus in swine.
abstract: Interactions between the viral surface glycoprotein haemagglutinin (HA) and the corresponding receptors on host cells is one important aspect of influenza virus infection. Mutations in HA have been described to affect pathogenicity, antigenicity and the transmission of influenza viruses. Here, we detected polymorphisms present in HA genes of two pandemic 2009 H1N1 (H1N1pdm09) isolates, A/California/04/2009 (Ca/09) and A/Mexico/4108/2009 (Mx/09), that resulted in amino acid changes at positions 186 (S to P) and 194 (L to I) of the mature HA1 protein. Although not reported in the published H1N1pdm09 consensus sequence, the P186 genotype was more readily detected in primary infected and contact-naïve pigs when inoculated with a heterogeneous mixed stock of Ca/09. Using reverse genetics, we engineered Ca/09 and Mx/09 genomes by introducing Ca/09 HA with two naturally occurring variants expressing S186/I194 (HA-S/I) and P186/L194 (HA-P/L), respectively. The Ca/09 HA with the combination of P186/L194 with either the Ca/09 or Mx/09 backbone resulted in higher and prolonged viral shedding in naïve pigs. This efficiency appeared to be more likely through an advantage in cell surface attachment rather than replication efficiency. Although these mutations occurred within the receptor-binding pocket and the Sb antigenic site, they did not affect serological cross-reactivity. Relative increases of P186 in publicly available sequences from swine H1N1pdm09 viruses supported the experimental data, indicating this amino acid substitution conferred an advantage in swine.
authors.affiliation: Virus and Prion Research Unit, National Animal Disease Center, USDA-ARS, Ames, IA, USA.
authors.forename: Alessio
authors.initials: A
authors.lastname: Lorusso
authors.affiliation: Laboratório de Virologia, Embrapa Suínos e Aves, Concórdia, Santa Catarina, Brazil.|Virus and Prion Research Unit, National Animal Disease Center, USDA-ARS, Ames, IA, USA.
authors.forename: Janice R
authors.initials: JR
authors.lastname: Ciacci-Zanella
authors.affiliation: Universidade de Passo Fundo, Brazil.|Virus and Prion Research Unit, National Animal Disease Center, USDA-ARS, Ames, IA, USA.
authors.forename: Eraldo L
authors.initials: EL
authors.lastname: Zanella
authors.affiliation: Virginia-Maryland Regional College of Veterinary Medicine, College Park, MD, USA.|Department of Veterinary Medicine, University of Maryland, College Park, MD, USA.
authors.forename: Lindomar
authors.initials: L
authors.lastname: Pena
authors.affiliation: Virginia-Maryland Regional College of Veterinary Medicine, College Park, MD, USA.|Department of Veterinary Medicine, University of Maryland, College Park, MD, USA.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Perez
authors.affiliation: Virus and Prion Research Unit, National Animal Disease Center, USDA-ARS, Ames, IA, USA.
authors.forename: Kelly M
authors.initials: KM
authors.lastname: Lager
authors.affiliation: Virus and Prion Research Unit, National Animal Disease Center, USDA-ARS, Ames, IA, USA.
authors.forename: Daniela S
authors.initials: DS
authors.lastname: Rajão
authors.affiliation: Virus and Prion Research Unit, National Animal Disease Center, USDA-ARS, Ames, IA, USA.
authors.forename: Crystal L
authors.initials: CL
authors.lastname: Loving
authors.affiliation: Virus and Prion Research Unit, National Animal Disease Center, USDA-ARS, Ames, IA, USA.
authors.forename: Pravina
authors.initials: P
authors.lastname: Kitikoon
authors.affiliation: Virus and Prion Research Unit, National Animal Disease Center, USDA-ARS, Ames, IA, USA.
authors.forename: Amy L
authors.initials: AL
authors.lastname: Vincent
mesh_terms: D000818:Animals; D015967:Gene Expression Regulation, Viral / Q000502:physiology*; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics / Q000378:metabolism*; D053118:Influenza A Virus, H1N1 Subtype / Q000235:genetics / Q000378:metabolism*; D009666:Nose / Q000821:virology; D009976:Orthomyxoviridae Infections / Q000635:transmission / Q000662:veterinary* / Q000821:virology; D011110:Polymorphism, Genetic; D013552:Swine; D013553:Swine Diseases / Q000635:transmission / Q000821:virology*; D017201:Virus Shedding / Q000235:genetics*
chemical_list: C543345:H1N1 virus hemagglutinin; D019267:Hemagglutinin Glycoproteins, Influenza Virus