Table 1.
Classification and gene origin of representative H1 subtype influenza viruses.
| HA Clade | Virus Name | Virus Name in this Study | Gene Origin | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| U.S. | Global | Subtype | PB2 | PB1 | PA | HA | NP | NA | M | NS | |||||||||||
| NA | NA | A/Brevig Mission/1/1918 A/South Carolina/1/1918 |
1918 a | H1N1 | |||||||||||||||||
| alpha | 1A.1-like | A/New Jersey/08/1976 | NJ/08 | H1N1v | |||||||||||||||||
| 1A.1.1 | A/Minnesota/45/2016 | MN/45 | H1N2v | * | * | * | |||||||||||||||
| beta | |||||||||||||||||||||
| 1A.2 | A/Texas/14/2008 | TX/14 | H1N1v | ||||||||||||||||||
| gamma | 1A.3.3.3 | A/Ohio/02/2007 | OH/02 | H1N1v | |||||||||||||||||
| 1A.3.3.3 | A/Ohio/09/2015 | OH/09 | H1N1v | * | |||||||||||||||||
| 1A.3.3.3 | A/Iowa/39/2015 | IA/39 | H1N1v | * | * | * | |||||||||||||||
| H1N1pdm09 | 1A.3.3.2 | A/Mexico/4482/2009 | Mex/4482 | H1N1pdm09 | * | * | * | * | * | * | * | * | |||||||||
| 1A.3.3.2 | A/California/04/2009 | CA/04 | H1N1pdm09 | * | * | * | * | * | * | * | * | ||||||||||
| 1A.3.3.2 | A/California/07/2009 | CA/07 | H1N1pdm09 | * | * | * | * | * | * | * | * | ||||||||||
| 1A.3.3.2 | A/Texas/15/2009 | TX/15 | H1N1pdm09 | * | * | * | * | * | * | * | * | ||||||||||
| delta | delta-like | 1B.2 | A/Brisbane/59/2007 | Bris/59 | H1N1 | ||||||||||||||||
| delta-1 | 1B.2.2.2 | A/Minnesota/19/2011 | MN/19 | H1N2v | |||||||||||||||||
| 1B.2.2.1 | A/Wisconsin/71/2016 | WI/71 | H1N2v | * | |||||||||||||||||
Clade was determined using the Swine H1 Clade Classification Tool (Influenza Research Database, www.fludb.org). Gene lineage origin was obtained from previous phylogenetic analyses [22,27,31,35]. Key: blue = classical swine H1 lineage, yellow = North American avian lineage, green = human seasonal lineage, red = Eurasian avian-like swine lineage, * H1N1pdm09 virus origin. Viruses containing triple reassortant internal gene (TRIG) cassette have NP, M, and NS genes from classical swine lineage H1N1 viruses, PB2 and PA genes from North American avian lineage viruses, and a PB1 gene from human seasonal-lineage viruses. NA – not applicable, sequence predates clade classification. a Genomic RNA of the 1918 virus was obtained from archived formalin-fixed lung autopsy materials and from frozen, unfixed lung tissues from an Alaskan influenza victim buried in permafrost during the pandemic [36].