An analysis on genetic characterization of HA1 gene of influenza virus subtype H3N2 circulated from 2001 to 2006 in Liaoning local area / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To understand the HA1 genetic variation characterization of influenza virus subtype H3N2 circulated from 2001 to 2006 in Liaoning local area.</p><p><b>METHODS</b>Viral RNA was extracted and transcribed into cDNA by reverse transcriptase and amplified by PCR. The product of PCR was purified by QIAgen purification kits,and sequenced by ABI 3100avant. The sequence data were analyzed phylogenetically by Sequence software with epidemic records. Finally, the phylogenetic trees were drawn according to deduced amino acid sequences of influenza virus H3N2 from 2000 to 2006 in the NCBI database.</p><p><b>RESULTS</b>The seven HA1domain sequences of H3N2 influenza viruses circulated from 2001 to 2006 in Liaoning local area had been analyzed. Compared with WHO 2004-2006 H3N2 vaccine A/California/7/2004, 12 bases had changed, 4 positions had amino acid substitution in 62 * > E, 182 T > 1,224 S > A,225 C > Y. 224 and 225 are RBS (Receptor binding site). The homology is lower than 98%. Phylogenetic tree showed Liaoning H3N2 2006 strains and Zhejiang 2005 strains were similar to WHO Northern hemisphere winter 2006-2007 Vaccine A/Wisconsin/67/2005 (H3N2)-like virus and grouped together to form an independent cluster even though several bases were still different.</p><p><b>CONCLUSION</b>The HA1 domain of HA gene of influenza viruses (H3N2) isolated from 2001-2006 in Liaoning local area showed base mutation, amino acid sequence difference compared to A/California/7/2004 (2005-2006 vaccine), suggesting it might be the main cause leading to the spread of influenza. The sequence analysis showed Liaoning 2006 H3N2 strains were similar to those from Southern area which suggested that further surveullance should be conducted to monitor the virus mutation in circulation.</p>

Influenza surveillance from 1999 to 2005 in Liaoning regions / 中华流行病学杂志

<p><b>OBJECTIVE</b>To investigate the prevalence and subtypes of influenza viruses in Liaoning regions from November 1999 to March 2005.</p><p><b>METHODS</b>Influenza virus was isolated by embryonated eggs together with cell culture and subtypes, identified by HI test.</p><p><b>RESULTS</b>During the study in 1999 - 2005, a total number of 2713 swab specimens were collected in different cities in Liaoning regions in which 188 strains were identified for influenza viruses with an average rate as 7.0%. A total number of 1466 swab specimens were collected by both Centers for Disease Control and Prevention in Dalian city and Liaoning province, and 167 strains were identified positive with an average rate of 11.4%. Influenza A3, A1 and B/Yamagata all appeared before March 2002 which were predominant strains. However, since then Influenza A1 has never appeared again in Liaoning regions and B showed some changes, from Yamagata to Victoria, the characteristics on the prevalence of influenza appeared only in the period of November to February.</p><p><b>CONCLUSION</b>It was meaningful to analyze the surveillance data of influenza in different years in Liaoning regions in order to better understand the characteristics of influenza and the shifting of subtype.</p>