Isolation And Identification Of Swine Flu Virus In Jilin Province And Isolates HA, NA Gene Sequence Analysis

In this study, a total of 13,063 samples for virus isolation were isolated to identification of subtype and analysis of genetic evolution, including 7,909 cases serum samples of swine and 5,154 cases of nose swabs and incident swine of lung and bronchial collected in Jilin province. The results showed that the three isolated swine influenza virus are subtypes of H1N1 which named A/swine/Jilin/1-1/2011, A/swine/Jilin/1-2/2011 and A/swine/Jilin/1-3/2011 based on naming standards of influenza virus. We analysed the genetic evolution of three strains of swine influenza viral subtypes for understanding the characteristics of molecular epidemiology. The HA gene of A/swine/Jilin/1-1/2011(H1N1) had 1638 bp that encoded a 532 amino acid protein. The NA gene had 1420 bp that encoded a 470 amino acid protein. The HA gene of A/swine/Jilin/1-2/2011(H1N1) had 1703 bp that encoded a 510 amino acid protein. The NA gene had 1404 bp that encoded a 456 amino acid protein. The HA gene of A/swine/Jilin/1-3/2011(H1N1) had 1745 bp that encoded a 568 amino acid protein. The NA gene had 1458 bp that encoded a 470 amino acid protein. Cleavage sites displayed three strains are low pathogenic strains. Glycosylation sites were not mutate that relatively conservative. Receptor binding sites displayed isolate potential sources of infection of poultry. Resistance gene sites of NA showed that these three swine influenza virus were effective to utilize neuraminidase inhibitor drugs. Phylogenetic analysis revealed that HA and NA gene of A/swine/Jilin/1-1/2011 and A/swine/Jilin/1-2/2011 were derived from wildfowl that were nearer relationships with avian influenza virus. HA gene of A/swine/Jilin/1-1/2011 and A/swine/Jilin/1-2/2011 were the nearest with H1N1 subtype influenza virus of A/wild duck/Korean/SH60/2004 isolated from Korean in 2004 and H1N2 subtype of A/duck/Hebei/843/2005 isolated from Hebei of China in 2005, respectively. The NA gene of both strains were the nearest with H1N1 subtype of A/duck/Eastern/China/103/2003, A/duck/EasternChina/152/2003 isolated from eastern of China. The big difference of the two strains was HA and NA gene of A/swine/Jilin/1-3/2011 derived from human influenza virus and swine influenza virus. HA genes were the nearest with virus subtype of H1N1 isolated from Shandong, Shanghai, Guangdong and Guangxi of China. NA genes were apparently near with virus subtype of H1N1 isolated from Shandong, Shanghai and Guangdong of China.