Surveillance and analysis of genetic characteristics of predominant strains of influenza A(H1N1) in Quanzhou city in 2009

Objective To understand the influenza A(H1N1) surveillance in Quanzhou city in 2009 and to analyze hemagglutinin(HA) and neuraminidase(NA) gene of influenza A(H1N1) virus and its genetic variation and molecular characteristics.Methods The specimens of throat swabs from the patients with influenza were collected and detected with real-time RT-PCR.Viruses were isolated with Macdin-Darby Canine Ridney cells and identified with serological test.Two influenza virus isolates were extracted,and their HA and NA genes were amplified with reverse transcription polymerase chain reaction(RT-PCR).The purified PCR products we sequenced.The data obtained were analyzed with DN AM AN sofwtare.Results To tally 200 influenza type A(H1N1) virus RNA were detected from 1020 specimens and 70 seasonal influenza virus RNA were detected.To tally 29 influenza A(H1N1) virus strains were identified.The nucleotide homology in the HA gene was highly homologous with that of in North America influenza pandemic.The aminoacids sequences deduced from the nueleotide sequences in HAregion of the isolated stra in had 22 variations compared with A/Brisbane/59/2007 vaccine stra in recommend by WHO.The characteristics of the receptor was human.The analysis of amino acid sequences of NA indicated that the virus possessed oseltamivir sensitivity.Conclusion The influenza A(H1N1) strains caused the epidemic in 2009 in Quanzhou city was highly homologous with that of in North America influenza pandemic.And they are antigenical and genetical differences compared to the vacc ne strain.