Objective To understand genomic characteristics of 2 strains of influenza A(H9N2)virus isolated from human infection cases in Anhui province in 2015.

Methods Two human infection with H9N2 virus were confirmed by national influenza surveillance laboratory network in Anhui through viral isolation in April and September, 2015, respectively. The full genomic sequences of the two viral isolates were analyzed in this study by using molecular bioinformatics software Mega 6.0.

Results Human infection with H9N2 virus was first reported in Anhui province. The analysis of genomic sequence showed that the HA and NA genes of the two H9N2 isolates belonged to A/Chicken/Shanghai/F/98(H9N2)-like lineage, and shared high identity with H9N2 virus circulating in poultry in 2013. The PB2 and MP genes belonged to the A/quail/Hong Kong/G1/97-like lineage, and shared high homology with H7N9, H10N8 or H6N2 viruses. The amino acid sequence alignment results showed that several mutations for human infection tropism presented in the two virus strains, including Q226L, H183N and E190T in HA; S31N in M2; 63-65 deletion in NA. In addition, the H9N2 influenza virus strains possessed the PSRSSR\GL motif in HA. Meanwhile several human-like signatures, including PA-100A, PA-356R and PA-409N were also found in the two virus strains.

Conclusion The H9N2 viruses isolated from human infection cases in Anhui province belonged to a reassortant virus originated from different lineage H9N2 avian influenza virus. The virus has possessed several human susceptibility locus.