Identification of dual receptor-binding specific strains of human H5N1 viruses in China

Abstract

Both the α2, 6 linkage and its topology on target cells were critical for human adaptation of influenza A viruses. The binding preference of avian flu virus H5N1 HA to the α2, 3-linked sialylated glycans is considered the major factor that limited its efficient infection in human. Currently, the switch in binding-specificity of human H5N1 viruses from α2, 3 to α2, 6-glycans did naturally occur, and limited humanto-human transmission was found. To monitor their potential adaptation in the human population, receptor-binding specificity surveillance was made in China. Here, the binding specificity of 32 human H5N1 virus strains isolated from 2003 to 2009 was demonstrated. Dual binding preference to α2, 3 and α2, 6-glycans were found in A/Guangdong/1/06 and A/Guangxi/1/08. Furthermore, both of them showed a high affinity to the long-branched α2, 6-glycans, which predominate on the upper respiratory epithelial in human. Our data suggests that the existence of H5N1 virus with binding specificity to humans should be of concern.