ETIDIOH - NEW

  Abstract Background :  The emergence of the highly pathogenic avian influenza (HPAI) H5N1 clade 2.3.4.4b in North America , beginning in February 2022, has highlighted the dynamic, unpredictable, and regionally variable risk of infections . Studies are needed to assess the spatiotemporal clustering of HPAI H5 at the interface between wild waterfowl and commercial poultry to understand and mitigate this risk .  Methods :  Publicly available data on HPAI H5 detections in wild birds and commercial poultry from January 2022 to January 2026 were analyzed at the county level. Retrospective space-time permutation models were used to identify and scan for clusters with higher than expected detection rates.  Results :  A total of 17,091 HPAI H5 detections were reported in wild birds across 1,467 county-level locations. Four species , Mallard ( Anas platyrhynchos ) (2,848 detections, 16.66%), Canada goose ( Branta canadensis ) (1,496, 8.75%), Green-winged teal ( An...

  Abstract A human infection with clade 2.3.4.4b H5N1 influenza A virus in Canada revealed minority variants E190D and Q226H in the hemagglutinin (HA) receptor-binding site (RBS). Because mutations at positions 190 and 226 have been associated with altered receptor specificity in other influenza subtypes, we investigated their impact on receptor binding in H5 HA . Using a recombinant protein approach and an ELISA-based glycan-binding assay , we assessed binding to representative avian- and human-type sialylated glycans . Both single mutations and their combination resulted in a complete loss of detectable binding to the tested glycans . To evaluate whether this phenotype was background-dependent, Q226H was additionally introduced into two other H5 HA proteins , each representing a distinct clade . In both cases, the mutation similarly abolished receptor binding . These findings independently validate recent glycan microarray observations and demonstrate that the patient-derived E19...