OBJECTIVETo analyze the etiology and genomic sequences of human infection of avian-origin influenza A(H7N9)virus from Zhejiang province.

METHODSViral RNA was extracted from patients of suspected H7N9 influenza virus infection and real-time RT-PCR was conducted for detection of viral RNA. All 8 segments of influenza virus were amplified by one-step RT-PCR and genomic sequences were assembled using the sequencing data. All the currently available HA and NA genes of the novel H7N9 virus, some other HAs from H7 subtype and NAs from N9 subtype were downloaded from public database for phylogenetic analysis, using the Mega 5.1 software. Mutations and variations were analyzed, using the genomic sequence data.

RESULTSReactions for influenza type A, subtype H7 and subtype N9 were all positive and all the genomic fragments were amplified for sequencing. After alignment, sequences were subjected for phylogenetic analysis. The results revealed highest homology with A/duck/Zhejiang/12/2011(H7N3)in HA gene and with A/wild bird/Korea/ A14/2011(H7N9)in NA gene of the H7N9 influenza virus. All 6 genes coding for internal proteins shared highest identities with H9N2 avian influenza which were circulated in the Chinese mainland, in the last two years. The sequenced virus showed Q226L mutation in HA protein, but E627K was not presented in PB2 protein of this virus. The E627K mutation was shared by all the other novel H7N9 viruses resulted in human infections through analysis on the currently available sequences.

CONCLUSIONUsing the clinical samples, both detection of the viral genes and amplification of all 8 segments of the novel H7N9 influenza virus were accomplished. High homology of the novel H7N9 influenza viruses was observed by phylogenetic test, using the currently available sequences. The virus showed Q226L mutation on HA protein but E627K did not present on PB2 protein of this virus.