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| Biological Characteristic of HA and NA Genes of H9N2 Avian Influenza Virus in Guangdong Province |
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| DOI：10.16768/j.issn.1004-874X.2023.05.012 |
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| Abstract: |
| 【Objection】This study aimed to monitor the genetic variation and molecular evolutionary trends of H9N2 avian influenza virus (AIV) in Guangdong, and provide reference data for the evolutionary analysis and prevention and control of H9N2 AIV in China. 【Method】The HA and NA genes of three H9N2 AIV strains isolated from Guangdong in 2022 were amplified, cloned, and sequenced. The DNAStar and PhyloSuite software were used for sequence assembly and alignment. The MEGA, Megalign, NetNGlyc 1.0 Server, and other software were used for genetic evolution, percent identity, receptor binding, protein activity, drug resistance, and glycosylation site analysis of their nucleotide and amino acid sequences. 【Result】The phylogenetic tree showed that the HA gene of the three isolates belonged to the clade h9.4.2.5 and the NA gene belonged to the clade 1. However, the nucleotide homology with the early strain was only 81.6%~91.7% and 88.2%~91.2%, formed new clade named clade h9.4.2.5c and clade 1.2, respectively. The nucleotide and amino acid sequence analysis revealed that the HA cleavage site was PSRSSR ↓ GLF. The receptor binding site underwent I155T, H183N, A190T/V, T212I, Q226L, and Q227M mutations. The glycosylation site underwent 218N non-glycosylation and acquired new glycosylation site at 313N. The NA stalk showed nine nucleotides deletion at positions 187-195 (ACAGAGATA), leading to the loss of three amino acids at positions 63-65 (TEI). The absorbtion site of NA on red blood cells showed K/E/S368N and D369N mutations. No related mutations to neuraminidase activity and drug resistance were found at the E119, D151, R152, R224, E276, R292, and R371. 【Conclusion】The HA and NA genes of the three H9N2 AIV isolated from Guangdong in 2022 had evolved into a new subgroup. Some mutaitons suggest that prevalent H9N2 in Guangdong may enhanc adaptability of mammals and its antigenicity has changed. Moreover, it has not yet acquired resistance to durgs oseltamivir and zanamivir. |
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