| evolution, global spread, and pathogenicity of highly pathogenic avian influenza h5nx clade 2.3.4.4. | novel subtypes of asian-origin (goose/guangdong lineage) h5 highly pathogenic avian influenza (hpai) viruses belonging to clade 2.3.4, such as h5n2, h5n5, h5n6, and h5n8, have been identified in china since 2008 and have since evolved into four genetically distinct clade 2.3.4.4 groups (a-d). since 2014, hpai clade 2.3.4.4 viruses have spread rapidly via migratory wild aquatic birds and have evolved through reassortment with prevailing local low pathogenicity avian influenza viruses. group a h5n ... | 2017 | 28859267 |