Neuraminidase reassortment and oseltamivir resistance in clade 2.3.4.4b A(H5N1) viruses circulating among Canadian poultry, 2024
Anthony V. Signore, Tomy Joseph, Charlene Ranadheera, Cassidy N. G. Erdelyan, Tamiru N. Alkie, Sugandha Raj, Lemarie Pama, Ifeoluwa Ayilara, Tamiko Hisanaga, Oliver Lung, Nathalie Bastien, Yohannes Berhane
Abstract
We report the detection of a clade 2.3.4.4b A(H5N1) reassortant virus with a neuraminidase surface protein derived from a North American lineage low-pathogenic avian influenza virus. This virus caused a widespread and ongoing outbreak across 45 poultry farms in British Columbia, Canada. Isolates from 8 farms reveal a mutation in the neuraminidase protein (H275Y) that is exceptionally rare among clade 2.3.4.4b viruses (present in 0.045% of publicly available clade 2.3.4.4b isolates). NA-H275Y is a well-known marker of resistance to the neuraminidase inhibitor oseltamivir. We demonstrate that this substitution maintains its resistance phenotype on the genetic background of H5N1 clade 2.3.4.4b viruses.