Background: To understand the characteristics of internal genes of two strains of influenza A(H9N2) virus isolated from men and on the basis of these to reveal the origin of these two strains of influenza A(H9N2)virus.
Methods: The target gene was amplified by RT-PCR,the PCR product was ligated with P GEM-T Vector (Promega Company, USA) at 4 degrees, the recombined plasmid was transferred into dH5a bacteria, and the positive colonies were selected and identified with restriction enzyme. Afterwards, they were sent to Liu He Tong Company in Beijing for nucleotide sequencing. Finally, phylogenetic analysis of the sequencing data was performed with MegAlign (version 1.03)and Editseq (Version 3.69) softwares.
Results: Internal genes of the two strains of H9N2 virus were G9 lineage. There was a slight difference in nucleotide sequence in PA gene between the two strains, whereas another five gene segments were identical to each other.
Conclusion: The genomes of the two strains of influenza A(H9N2)virus were G9 lineage.They were transmitted to men separately from different avian sources with different characteristics of gene of influenza A(H9N2) virus, respectively.