Answer:
H1N1 virus with genes of avian origin
Step-by-step explanation:
The outbreak was caused by an influenza type, where the subtype of it is know as H1N1 virus.(. Characterization of five of the eight RNA segments of the 1918 influenza virus indicates that it was the common ancestor of both subsequent human and swine H1N1 lineages, and experiments testing models of virulence using reverse genetics approaches with 1918 influenza genes have begun in hopes of identifying genetic features that confer virulence in humans..... EXTRACTED FROM A TEXT FOR MORE INFO)