title: Isolation of a novel swine influenza virus from Oklahoma in 2011 which is distantly related to human influenza C viruses.
abstract: Of the Orthomyxoviridae family of viruses, only influenza A viruses are thought to exist as multiple subtypes and has non-human maintenance hosts. In April 2011, nasal swabs were collected for virus isolation from pigs exhibiting influenza-like illness. Subsequent electron microscopic, biochemical, and genetic studies identified an orthomyxovirus with seven RNA segments exhibiting approximately 50% overall amino acid identity to human influenza C virus. Based on its genetic organizational similarities to influenza C viruses this virus has been provisionally designated C/Oklahoma/1334/2011 (C/OK). Phylogenetic analysis of the predicted viral proteins found that the divergence between C/OK and human influenza C viruses was similar to that observed between influenza A and B viruses. No cross reactivity was observed between C/OK and human influenza C viruses using hemagglutination inhibition (HI) assays. Additionally, screening of pig and human serum samples found that 9.5% and 1.3%, respectively, of individuals had measurable HI antibody titers to C/OK virus. C/OK virus was able to infect both ferrets and pigs and transmit to naive animals by direct contact. Cell culture studies showed that C/OK virus displayed a broader cellular tropism than a human influenza C virus. The observed difference in cellular tropism was further supported by structural analysis showing that hemagglutinin esterase (HE) proteins between two viruses have conserved enzymatic but divergent receptor-binding sites. These results suggest that C/OK virus represents a new subtype of influenza C viruses that currently circulates in pigs that has not been recognized previously. The presence of multiple subtypes of co-circulating influenza C viruses raises the possibility of reassortment and antigenic shift as mechanisms of influenza C virus evolution.
authors: Newport Laboratories, Worthington, Minnesota, United States of America. bhause@newportlabs.com
authors: Ben M
authors: BM
authors: Hause
authors: Mariette
authors: M
authors: Ducatez
authors: Emily A
authors: EA
authors: Collin
authors: Zhiguang
authors: Z
authors: Ran
authors: Runxia
authors: R
authors: Liu
authors: Zizhang
authors: Z
authors: Sheng
authors: Anibal
authors: A
authors: Armien
authors: Bryan
authors: B
authors: Kaplan
authors: Suvobrata
authors: S
authors: Chakravarty
authors: Adam D
authors: AD
authors: Hoppe
authors: Richard J
authors: RJ
authors: Webby
authors: Randy R
authors: RR
authors: Simonson
authors: Feng
authors: F
authors: Li
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood*; D000956:Antigens, Viral / Q000276:immunology; D001483:Base Sequence; D018929:Cell Culture Techniques; D005289:Ferrets; D016679:Genome, Viral / Q000235:genetics*; D006385:Hemagglutination Inhibition Tests; D006389:Hemagglutinins, Viral / Q000235:genetics / Q000378:metabolism; D058507:Host Specificity; D006801:Humans; D009982:Gammainfluenzavirus / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification* / Q000648:ultrastructure; D008297:Male; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009825:Oklahoma; D009976:Orthomyxoviridae Infections / Q000276:immunology / Q000635:transmission / Q000821:virology*; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D013552:Swine; D013553:Swine Diseases / Q000276:immunology / Q000635:transmission / Q000821:virology*; D014760:Viral Fusion Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D000914:Antibodies, Viral; D000956:Antigens, Viral; D006389:Hemagglutinins, Viral; D014760:Viral Fusion Proteins; C060814:hemagglutinin esterase