title: Experimental infection of pigs with the human 1918 pandemic influenza virus.
abstract: Swine influenza was first recognized as a disease entity during the 1918 "Spanish flu" pandemic. The aim of this work was to determine the virulence of a plasmid-derived human 1918 pandemic H1N1 influenza virus (reconstructed 1918, or 1918/rec, virus) in swine using a plasmid-derived A/swine/Iowa/15/1930 H1N1 virus (1930/rec virus), representing the first isolated influenza virus, as a reference. Four-week-old piglets were inoculated intratracheally with either the 1930/rec or the 1918/rec virus or intranasally with the 1918/rec virus. A transient increase in temperature and mild respiratory signs developed postinoculation in all virus-inoculated groups. In contrast to other mammalian hosts (mice, ferrets, and macaques) where infection with the 1918/rec virus was lethal, the pigs did not develop severe respiratory distress or become moribund. Virus titers in the lower respiratory tract as well as macro- and microscopic lesions at 3 and 5 days postinfection (dpi) were comparable between the 1930/rec and 1918/rec virus-inoculated animals. In contrast to the 1930/rec virus-infected animals, at 7 dpi prominent lung lesions were present in only the 1918/rec virus-infected animals, and all the piglets developed antibodies at 7 dpi. Presented data support the hypothesis that the 1918 pandemic influenza virus was able to infect and replicate in swine, causing a respiratory disease, and that the virus was likely introduced into the pig population during the 1918 pandemic, resulting in the current lineage of the classical H1N1 swine influenza viruses.
authors.affiliation: National Centre for Foreign Animal Disease, Canadian Food Inspection Agency, Winnipeg, Manitoba, Canada. hweingartl@inspection.gc.ca
authors.forename: Hana M
authors.initials: HM
authors.lastname: Weingartl
authors.forename: Randy A
authors.initials: RA
authors.lastname: Albrecht
authors.forename: Kelly M
authors.initials: KM
authors.lastname: Lager
authors.forename: Shawn
authors.initials: S
authors.lastname: Babiuk
authors.forename: Peter
authors.initials: P
authors.lastname: Marszal
authors.forename: James
authors.initials: J
authors.lastname: Neufeld
authors.forename: Carissa
authors.initials: C
authors.lastname: Embury-Hyatt
authors.forename: Porntippa
authors.initials: P
authors.lastname: Lekcharoensuk
authors.forename: Terrence M
authors.initials: TM
authors.lastname: Tumpey
authors.forename: Adolfo
authors.initials: A
authors.lastname: García-Sastre
authors.forename: Jürgen A
authors.initials: JA
authors.lastname: Richt
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology; D004195:Disease Models, Animal; D004196:Disease Outbreaks / Q000266:history; D005260:Female; D049673:History, 20th Century; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology / Q000302:isolation & purification / Q000472:pathogenicity / Q000502:physiology*; D053122:Influenza A Virus, H3N2 Subtype / Q000502:physiology; D051379:Mice; D009976:Orthomyxoviridae Infections / Q000453:epidemiology / Q000266:history / Q000473:pathology* / Q000821:virology*; D012367:RNA, Viral / Q000235:genetics; D015996:Survival Rate; D013552:Swine / Q000821:virology*
chemical_list: D000906:Antibodies; D012367:RNA, Viral