ObjectiveTo disclose the epidemiological characteristics of the first human case of H9N2 subtype avian influenza and genetic characteristics of hemagglutinin (HA) gene of H9N2 avian influenza virus in Jiangsu province.
MethodsReverse transcription polymerase chain reaction (RT-PCR) assay was used to detect the nucleic acid of influenza virus A/B and various subtypes from throat swab specimens of patients with acute and severe respiratory infections of unknown cause. Sanger method was used to sequence the vial HA gene of H9N2 positive specimens. N-J phylogenetic tree of HA gene was constructed by using MEGA X software.
ResultsThe first laboratory confirmed case of human infection with H9N2 avian influenza virus in Jiangsu province in March 2019 was reported by Suzhou Center for Disease Control and Prevention. Sequence analysis of the HA gene showed that the A/Suzhou/S683/2019 (H9N2) strain belonged to Y280-like sub-lineage of the Eurasian lineage, which had 99.23% nucleic acid identity with A/chicken/Shanghai/S1171/2018 (H9N2) strain. The amino acid sequence of the HA protein cleavage site is PSRSSR↓GLF, and the key amino acid in receptor binding site shared Q226L mutation. The location of potential glycosylation sites of HA protein of A/Suzhou/S683/2019 (H9N2) have changed.
ConclusionsThe H9N2 avian influenza virus obtained from the first case in Jiangsu province has low pathogenicity, but it may have acquired part of the ability to adapt to human hosts.