Effects Of Chicken ST3GAL I Expression On The Reproduction Of H9 AIV In MDCK Cells

Since the first report of the H9N2 subtype AIV in chine 1994, it has become a main subtype.The incident that humans were infected by avian influenza virus shows avian influenza virus can infect humans directly without prior adaptation.threrfore, the study of H9N2 avian influenza virus, not only has very important academic significance in virology, veterinary science and other disciplines, but also has great social significance in terms of public health.A major determinant of influenza infection is the presence of virus receptors on susceptible host cells to which the viral haemagglutinin is able to bind. Avian viruses preferentially bind to sialic acid a2,3-galactose (SAa2,3-Gal) linked receptors, whereas human strains bind to sialic acid a2,6-galactose (SAa2,6-Gal) linked receptors. While SIVs can bind to both receptors.the differences in viral receptor has a significant impact on the infection and replication of the virus.Becouse of serious problems such as the quality is difficult to control, long cycle, limited sources of chick embryo exist in the production of Avian influenza vaccine, the World Health Organization highly recommend countries using cell culture to produce influenza virus vaccine.The MDCK line is commonly used as one of the cell lines for the production of influenza vaccine, which posess the characteristic of simple culture,rapid proliferation and sensitive to a variety of influenza virus recerch found that MDCK cells expressing both SAα2,3Gal, and SAα2 6Gαl. Avian influenza virus HA binding SAa2,3Gal mainly, but the abundance of the receptor on MDCK cells is not high, resulting in low virus titer of the avian influenza virus in these cells.ST3GAL I capable of catalyzed the form of alpha2,3 glycosidic linkage structure specifically in cell surface.Therefore, to constructe the eukaryotic expression ST3GALI plasmid, designated pcDNA3.1-ST3Gal I, in this study complete ORF District of ST3Gal I gene was cloned and directionally connected to the pcDNA3.1 (+) eukaryotic expression vector. Then transient transfection MDCK cells, semi-quantitative RT-PCR results showed that ST3Gal I gene is highly expressed at the mRNA level.16 H9 subtype of avian influenza viruses isolated in recent years were inoculated transfection and the non-transfected MDCK cells group, observed cell lesions,then carried out the HA and TCID50 detection.The results showed that in transfected cells, viral titers were higher than untransfected cells. The test proved that virus titerf H9 subtype of avian influenza can be improved by expression of ST3Gal I gene in MDCK cells, which provides a theoretical basis for the research of the characteristics of avian influenza virus binding receptores and large-scale production cells influenza vaccine.