ObjectiveTo analyze the complete genome sequence and phylogenetic structure of a wild bird-derived H1N1 avian influenza virus (AIV) in the northern Tianshan Mountain.
MethodsIn November 2018, 320 samples of fresh wild bird feces were collected from several reservoirs in the middle part of northern Tianshan Mountain. Chicken embryo inoculation test, hemagglutination inhibition test and RT-PCR with PB1 universal primer were used to isolate and identify AIVs. Eight fragments of the viral genome were amplified with the universal primers of influenza A virus and the whole viral genome was sequenced. Pairwise sequence alignments and analysis of phylogenetic and molecular characteristics were performed by BLAST, Clustal W, MEGA7.0 and MegAlign software.
ResultsInfluenza viruses were isolated and identified from six samples of wild bird feces with a positive rate of 1.88%. One of them was H1N1 AIV, named A/wild bird/Xinjiang/010/2018 (H1N1) (XJ-H1N1). The eight gene segments of XJ-H1N1 were all derived from AIVs isolated from wild ducks of Anseriformes. The surface genes of HA and NA were Eurasian lineages and derived from H1N1 isolated from Mongolian Anas platyrhynchos and H3N1 isolated from Bangladesh wild duck, respectively. The six internal genes were derived from H6N8 isolated from Anas strepera in Siberia, H7N3 isolated from Anas clypeata and teal in Egypt, and H7N5 isolated from wild birds such as Anas platyrhynchos in the Netherlands. The HA cleavage site of XJ-H1N1 contained only one basic amino acid, suggesting that it was a low pathogenic AIV. Amino acids at positions 190 and 225 of HA receptor binding sites were E and G (H3 count), which could bind both α2, 3 galactoside sialic acid (SAα2, 3Gal) and SAα2, 6Gal receptors. T200A and E227A mutations in HA amino acid sequences and P42S mutation in NS1 amino acid sequences could all enhance the replication ability and pathogenicity of the virus in mammalian cells.
ConclusionsA low pathogenic H1N1 AIV, XJ-H1N1, was isolated from wild birds in the northern Tianshan Mountain, resulting from multiple reassortments of AIVs carried by migrating wild ducks. The replication capacity and pathogenicity of XJ-H1N1 in mammalian cells might be enhanced. Moreover, the virus could bind both SA 2-3gal and SA 2-6gal receptors.