| Objective: To study the influenza activity and the characteristics of HA gene of influenza virus isolated in Dalian during 2005~2009 season. To elucidate the relationship between the influenza epidemic/outbreak and the variation of HA gene of the virus.In order to provide the scientific basis of the prevention and treatment of influenza.Methods: The data of ILI (Influenza-like illness) were collected by Influenza surveillance information system during January 2005 to March 2009.The specimens were inoculated into MDCK cell flasks for influenza virus. The isolates were identified for influenza virus type and subtype by hemagglutinin inhibition. To analyze the characteristics of HA gene of influenza isolated from Dalian in 2005-2009, and to elucidate the relationship between the influenza epidemic and the variation of HA gene of the virus. The viruses were isolated and propagated by MDCK cell. RNAs were extracted and their HA genes were amplified by reverse transcription polymerase chain reaction (RT-PCR). The purified PCR products were sequenced. Using the DNAStar software, the nucleotide and amino acid sequences on HA protein molecular of influenza virus were compared with that of influenza viruses which were epidemical in recent years or vaccine complement recommended by WHO.Results:1. January 2005~December 2009, 87 influenza strains were isolated from 1291 clinical specimens from ILIs by MDCK(Madin-Darby canine kidney)cells, Of these, 39 (44.83%) influenza A (H1N1) viruses, and 16 (18.39%) influenza A (H3N2) viruses, and 32 (36.78%) B viruses.2. Influenza virus type A1 HA1 gene analysis showed that: The nucleotide homology of influenza A virus isolated from Dalian was 97.3%~99.9% in 2005~2009. Compared with influenza virus vaccine strains A/New Caledonia/20/99, the nucleotide homology was 98.6%~99.2% in Dalian during 2005~2006; Compared with influenza virus vaccine strains A/Solomon Islands/3/2006, the nucleotide homology was 95.8%~97.3% in Dalian in 2007; Compared with influenza virus vaccine strains A/Brisbane/59/2007, the nucleotide homology is 97.0%~99.7% during 2008~2009.Compared with standard sequences, there were 11, 9, 15, 15 mutations in the amino acid sequences of virus strains isolated in 2005, 2006, 2007 and 2008 respectively.3. Influenza virus type A 3 HA1 gene analysis showed that: The HA1 genes of the influenza H3N2 viruses isolated in Dalian during 2005~2007 influenza season were similar to A/ Fujian/411/ 2002 and A/ Wisconsin/ 67/ 2005, which were the vaccine strain recommend by WHO in that season. There was an identity of 98.00%~99.10% in nucleotide sequence between them. In 2005 and 2007, six and fourteen amino acids were substituted in HA1 and two located in B antigenic determinant sites (197S>N, 194V> G) respectively.4. HA gene analysis of influenza virus type B showed that: The Yamagata-like virus circulated in 2007~2008.Compared with A/wisconsin/67/05 vaccine strain recommended by WHO, there was an identity of 97.3-97.8% in nucleotide sequence and two differences. Eight amino acids were substituted in HA1 and two of them located in antigenic determinant sites (131L>P, 196D> N). There was one more glycosylation site at 196th site.5. The prediction of circulation strength of influenza virus in Dalian confirmed basically to the actual circumstances based on the 63 influenza virus HA gene sequencing and analysis of 2005~2009.Conclusion:1. Kinds of influenza virus isolated from Dalian confirm to circulated state of north of China yearly.2. There are some differences between Influenza virus isolated from Dalian and vaccine strain recommended by WHO. 3. Gene sequence database of all kinds of Influenza virus isolated from Dalian bythe project can find useful mutated virus. It can also provide theory basis and technology support to the future prevention and control of Influenza prevalence and outbreak. It is very useful to control Influenza spread and prevalence. |
PDF Full Text Request