title: On the origin of pandemic influenza viruses.
mesh_terms: D000818:Animals; D000914:Antibodies, Viral; D000956:Antigens, Viral; D002645:Chickens; D006389:Hemagglutinins, Viral; D008055:Lipids; D008854:Microscopy, Electron; D008970:Molecular Weight; D009154:Mutation; D009439:Neuraminidase / Q000032:analysis; D009698:Nucleoproteins / Q000032:analysis; D009975:Orthomyxoviridae / Q000201:enzymology; D012367:RNA, Viral / Q000032:analysis; D011995:Recombination, Genetic; D013552:Swine; D009626:Terminology as Topic; D014422:Turkeys; D014764:Viral Proteins / Q000032:analysis
chemical_list: D000914:Antibodies, Viral; D000956:Antigens, Viral; D006389:Hemagglutinins, Viral; D008055:Lipids; D009698:Nucleoproteins; D012367:RNA, Viral; D014764:Viral Proteins; D009439:Neuraminidase