A new clade 2.3.4.4b H5N1 highly pathogenic avian influenza genotype detected in Europe in 2021

Despite their widespread distribution, the clade 2.3.4.4b H5N1 viruses have so far only been known in a single genotype variant in Europe. In the study presented, we report the first detection of a new highly pathogenic avian influenza H5N1 genotype in geese and ducks from a backyard farm in the Czech Republic. Phylogenetic analysis has revealed that the Czech H5N1 virus retained the A/Eurasian_Wigeon/Netherlands/1/2020-like backbone with an altered PB2 segment from co-circulating low pathogenic avian influenza viruses.