Objective To understand the antigenic and genetic characteristics of highly pathogenic avian influenza H5N1 viruses isolated from poultry related environments of surrounding areas of Qinghai Lake.

Methods Poultry and wild birds related environments from surrounding areas of Qinghai lake were collected and handled. Viruses were isolated with embryonated chicken eggs. The virus subtyping was performed by real-time RT-PCR. The highly pathogenic avian influenza H5N1 viruses were chosen to conduct next generation sequencing and hemagglutination inhibition (HI) assay.

Results In total of 19 H5N1 virus strains were isolated, they were all from poultry related environments and collected in January-March of year 2013. Seven representative highly pathogenic avian influenza H5N1 viruses were sequenced and analyzed for antigenicity. According to phylogenetic analysis of HA gene, 6 viruses were belong to clade 2.3.2.1c except A/Environment/Qinghai/XN02032/2013 which belongs to clade 7.2. Antigenic analysis showed that 6 viruses were antigenically similar to A/Barn swallow/Hong Kong/D10-1161/2010, while A/Environment/Qinghai/XN02032/2013 presented low reaction with all reference antisera.

Conclusions The existence of highly pathogenic avian influenza H5N1viruses in poultry related environments of surrounding areas of Qinghai Lake was confirmed. The status of highly pathogenic avian influenza H5N1 viruses with evolution diversity emphasized the necessary of strengthening the avian influenza surveillance in these areas.