ABSTRACT
Objective To obtain the information of the 2009 influenza outbreak and the variations of influenza virus strains in quanzhou, and explore the relationship between the genetic variation of influenza virus and influenza epidemic. Methods During the influenza outbreak in quanzhou,one hundred and ninetyeight throat swabs specimens from the patients with influenza were collected. Viruses were isolated with MDCK cells and identified with serological test, followed by real-time RT-PCR. RNA of four influenza virus strains were extracted, then HA1 gene was amplified by RT-PCR. The purified PCR products were sequenced. The data were analyzed with the software DNAstar megalign. Results Total 98 pieces of H3N2 subtype influenza virus nucleic acid were detected in 198 throat swabs specimens,among which 62 influenza virus strains were identified as subtype influenza A( H3N2 ). The sequencing results of HA1 gene in these positive strains showed that their genetic characterization were more closed to strains A/Ningbo/333/2008 with a nucleotide homology of 98.7%, which was 96.8% as compared with A/Xiamen/70/2004. The amino acids sequences deduced from the nucleotide sequences in HA1 region of the isolated strain had 7 mutant sites compared with A/Brisbane/10/2007 vaccine strain. One variant amino acids were found located in the antigenic determinant sites A( 144 ), two were in the sites B( 158,189 ). Phylogenetic analysis also confirmed the difference in HAl domain. Conclusion The influenza virus strains causing the flu outbreak among some communities of quanzhou in 2009 are subtype influenza A ( H3N2 ), whose genetic characterization and antigenicity were different from the vaccine strain.
ABSTRACT
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.