Nucleic acid detection and genomic sequence analysis of one H5N1 avian influenza virus from wide birds around Qinghai Lake

In August 2022, there was an unusual mortality event among wild ducks in Qinghai Province, China. The nucleic acid was extracted from the collected tissues of the dead wild ducks, and the M gene of avian influenza virus(AIV) was first detected by universal RT-PCR and then the H5/H7/H9 specific genes were detected by using subtyping primers. The wild duck tissues were found to contain the nucleic acid of H5 subtype AIV. The complete geneome of detected AIV was further sequenced by next generation sequence, and the 8 segments of the AIV were obtained. Analysis using Basic Local Alignment Search Tool revealed that, except for the NS gene, the other segments showed the highest homology with those of the H5N1 subtype. The HA gene cleavage site exhibited the characters of highly pathogenic avian influenza (HPAI) virus. The strain detected from the wild ducks was named A/Wigeon/Qinghai/2022(H5N1). Genetic evolution analysis of the HA gene indicated that A/Wigeon/Qinghai/2022(H5N1) belonged to the 2.3.4.4b subclade including H5N1 and H5N8, which has been circulating in wild birds in recent years, while showing a distant genetic relationship with the strains that were prevalent in Qinghai Province from 2005 to 2015. This study indicates that the genetic diversity of H5 subtype AIV derived from wild birds in Qinghai Lake is abundant, emphasizing the need for continuous monitoring of AIV carried by wild birds in the area.