vol21no7_pdf-version

Receptor Binding of Influenza A(H10N8) VirusFigure 1. Receptor bindingspecificity of hemagglutininof influenza A(H10N8) virusH10-JD346. A) Binding ofrecombinant hemagglutinins toglycans in a solid-phase bindingassay. Results are means ±SEM of triplicate samples.PAA, polyacrylamide. B) Flowcytometry–based assay. H3-P99(human), H5-Viet (avian originisolated from a human case),and H10-mallard (avian) viruseswere included in the analysisfor comparison and as controls.Values at the top right of the dotplots indicate percentage of cellsexpressing matrix protein 2 (M2).FSC, forward-scattered light;FITC, fluorescein isothiocyanate.caused by this virus subtype is currently ongoing in Europe(5). A study by Beare and Webster showed that≈50% of volunteers experimentally infected with influenzaA(H10N7) virus shed virus (15), which our data suggestsmight be caused by initial attachment to the upper respiratorytract. Immune responses were not detected in thesevolunteers, and mild, if any, symptoms developed, whichindicated limited virus replication.The low incidence of H10 influenza virus indicates alimited pandemic potential of H10N7 and H10N8 viruses.Therefore, further changes in receptor binding, as well asacquisition of genomic segments from other avian influenzavirus strains through co-infection, would be requiredto increase fitness and transmissibility in mammals. IsolateH10-JD346 amino acid sequence had a mixture of E andK in position 627 of basic polymerase protein 2; the K627Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 21, No. 7, July 2015 1199