title: Significant antigenic drift within the influenza equi 2 subtype in Sweden.
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000032:analysis*; D006385:Hemagglutination Inhibition Tests; D006734:Horse Diseases / Q000276:immunology*; D006736:Horses / Q000276:immunology; D009975:Orthomyxoviridae / Q000302:isolation & purification; D009976:Orthomyxoviridae Infections / Q000276:immunology / Q000662:veterinary*
chemical_list: D000914:Antibodies, Viral