Abstract
Since December 2013, at least three cases of human infections with H10N8 avian influenza virus have been reported in China, two of them being fatal. To investigate the epidemic potential of H10N8 viruses, we examined the receptor binding property of the first human isolate, A/Jiangxi-Donghu/346/2013 (JD-H10N8), and determined the structures of its haemagglutinin (HA) in complex with both avian and human receptor analogues. Our results suggest that JD-H10N8 preferentially binds the avian receptor and that residue R137-localized within the receptor-binding site of HA-plays a key role in this preferential binding. Compared with the H7N9 avian influenza viruses, JD-H10N8 did not exhibit the enhanced binding to human receptors observed with the prevalent H7N9 virus isolate Anhui-1, but resembled the receptor binding activity of the early-outbreak H7N9 isolate (Shanghai-1). We conclude that the H10N8 virus is a typical avian influenza virus.
Highlights
Since December 2013, at least three cases of human infections with H10N8 avian influenza virus have been reported in China, two of them being fatal
We find that JD-H10N8 preferentially bound the avian receptor, with limited binding to the human receptor (Fig. 1a), which is similar to the SH-H7N9 virus (Fig. 1b), the early isolate of the 2013 outbreak in China
The human influenza virus CA04-H1N1 preferentially bound the human receptor (Fig. 1d) and the avian influenza virus AH05-H5N1 preferentially bound the avian receptor (Fig. 1e). These data demonstrate that the JD-H10N8 virus has similar receptor-binding properties to the early H7N9 isolate of SH-H7N9 (Shanghai-1) and remains an avian virus with the potential for sporadic human infections
Summary
Since December 2013, at least three cases of human infections with H10N8 avian influenza virus have been reported in China, two of them being fatal. Since the first human infection with avian influenza A (H5N1) virus was reported in Hong Kong in 1997 (refs 5,6), the H5N1 virus has caused more than 600 cases of human infections, with a fatality rate of B60% (http://www.who.int/influenza/human_animal_ interface/H5N1_cumulative_table_archives/en/). The influenza A H7N9 virus was first identified in China in 2013 and has caused more than 400 cases of human infections, with a fatality rate of B30% (http://www.who.int/influenza/human_animal_ interface/influenza_h7n9/en/). Exploring the epidemic potential of this H10N8 virus is crucial for the development of effective preventive and therapeutic measures We evaluate this strain’s receptor-binding properties and the molecular basis for its activity. Crystal structures of H10 protein in complex with avian or human receptor analogues reveal that residue R137, located in the receptor-binding site of HA, plays a key role in the preferential binding to the avian receptor
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