Influenza H1N1 surveillance and analysis of genetic characteristics of predominant strains in Quanzhou during 2009
Objective To investigate the influenza H1N1 virus surveillance of 2009 in Quanzhou,and analyze the HA and NA gene of influenza H1N1 virus, explore its genetic variation and molecular characteristics. Methods During the influenza H1N1 virus surveillance in Quanzhou,specimens of throat swabs from the patients with influenza were collected, and detected by real-time RT-PCR. Viruses were isolated with MDCK cells and identified with serological test. Two influenza virus isolates were extracted, and their HA and NA genes were amplified by RT-PCR. The purified PCR products were sequenced. The data obtained were analyzed with the software DNAMAN. Results Of 1020, influenza H1N1 virus RNA was detected in 200 specimens, seasonal influenza virus RNA was detected in 70 specimens. A total of 29 influenza A H1N1 virus strains were isolated. The nucleotide homology in the HA gene was highly homologous with that of pandemic influenza virus in North America. The amino acids sequences deduced from the nucleotide sequences in HA region of the isolated strain had 22 variations compared with A/Brisbane/59/2007 vaccine strain recommend by WHO,the characteristics of α2,6 sialic acid receptor binding remained. The analysis of amino acids sequences of NA indicated that this virus possessed Oseltamivir sensitivity. Conclusion The causative influenza H1N1 strains in Quanzhou is highly homologous with that of pandemic influenza in North America, and it is antigenically and genetically different from the vaccine strain. 
 
Key words: 
H1N1 influenza virus;  Real-time RT-PCR;  Sequence analysis