Multiple Introductions of Reassorted Highly Pathogenic Avian Influenza H5Nx Viruses Clade 2.3.4.4b Causing Outbreaks in Wild Birds and Poultry in The Netherlands, 2020-2021

ABSTRACT Highly pathogenic avian influenza (HPAI) viruses of subtype H5Nx caused outbreaks in poultry, captive birds, and wild birds in the Netherlands between October 2020 and June 2021. The full genome sequences of 143 viruses were analyzed. HPAI viruses were mainly of subtype H5N8, followed by H5N1, but also viruses of subtypes H5N3, H5N4, and H5N5 were detected. At least seven distinct genotypes were found, carrying closely related H5 segments belonging to clade 2.3.4.4b. Molecular clock analysis suggests that the reassortments of the NA gene segments likely occurred before the introductio... Mehr ...