Apoptosis Induced By Two H5N1 Avian Influenza Viruses

Highly pathogenic avian influenza(HPAI) is a fulminating and rapidly fatal systemic disease in domestic poultry.In recent years, H5N1 avian influenza viruses have crossed the species barrier to directly cause fatal disease in humans.Discerning how influenza viruses interact with the host is crucial for a better understanding of viral pathogenesis.Influenza viruses induce apoptosis through mechanisms involving the interplay of cellular and viral factors that may depend on the cell type. The question still remains as to whether virus-induced apoptosis is advantageous for viral spread or is advantageous to the host, the mechanism of influenza virus-induced apoptosis was not know in detail. These studies will provide our undersuanding of viral pathogenesis for influenza viral infection, based on NS1-induced apoptosis and exploring the apoptosis of CEF cell and mammal induced by two avian influenza viruses more.In this report, two avian influenza viruses(AIV) A/Duck/Guangdong/40/2000 (H5Nl)(DKGD/40/00) and A/Duck/Guangxi/35/2001 ( H5N1 ) (DKGX/35/01) were choosed according to their differently biololgical characteristic in evidence. DKGD/40/00 and DKGX/35/01 belong to HPAIV for domestic poultry, but DKGD/40/00 was infectant, DKGX/35/01 was infectant and fatal in mice. Two avian influenza viruses were cloned, then the transfer efficiency and transient expression of NS1 genes were constructed to the eukaryotic vector pIRES2-EGFP were tested using fluorescent microscope, the relation NSl genes with apoptosis was observed by TUNEL and flow cytomentry. Results shown that the expression of NS 1 genes of AIV was sufficient to induce apoptosis in Hela cell, apoptosis rate was as high as 15.29%, however, the two had no obvious difference. It was impossible that the individual influenza virus gene (NS1) may be analyzed the relation NS1-induced apoptosis with viral titers or viral spread.To observe the apoptosis of CEF induced by two avian influenza viruses, their apoptosis profiles were observed and detected after CEF was infected by two avian influenza viruses. Results showed that the infected cells showed apparent changes in growth characteristeics and morphologies; DNA agarose gel electrophoresis showedcharacteristic "ladder"; Apoptotic peaks were observed by flow cytometry. Apoptosis rate was as high as 23.64%, and the two had obvious difference. Conclusion suggested that H5N1 influenza virus can induce CEF cell to undergo apoptosis; and it may analyze the relation induced-apoptosis with viral titers.With the HongKong outbreak of H5N1 influenza, it became clearly that the virulence potential of these viruses extended to humans.Based on the molecular level and the cellular level,using immunohistochemistry staining to understand the contribution of apoptosis to avian influenza viruses for mammmal , viral antigens were also detected in hearts liver, spleen, lung, kidney brain and pancreas after BALB/C mice were infected by two avian influenza viruses, and apoptosis was observed by TUNEL. These results indicated that apoptosis did occur in virulent avian influenza viruses infection in BALB/C mice,and may contribute to the lethality of the virus.