The Influenza Virus Induced Apoptosis

Objective: To explore the mechanism of influenza virus which induces cell death and results in immunosupression. Methods:lnfluenza virus- induced cell death was determined by calculating percentage of apoptotic cells, observing morphological changes ,analyzing DNA fragmentation and flow cytometry. Results: (1)Influenza virus-infected cultured MDCK(Madin- Darby canine kidney)cells were found to have characteristic morphological changes of apoptosis by light and electron microscopy,sucli as extensive condensation of chromatin into dense masses and concentration of cytoplasm associated with lots of cytoplasmic vacuolization.(2)The percentage of MDCK cells apoptosis of activated virus-infected group was significantly higher than that of inactivated virus-infected group and negative control group(PO.05).(3)By analysis of DNA fragmentation of MDCK cells, the activated virus-infected group showed a typical ladder-lik& map, while, only a large fragment of DNA map was observed in the inactivated virus-infected group and negative control group.(4)Sub G1t peak of MDCK cells of activated virus-infected group was significantly higher than that of negative control group.(5)Thepercentage of apoptosis of P11A-stimulated T lymphocytes of activated virus- infected group was comparable with that of inactivated virus-infected group or negative control group(P>O.05).By analyzing DNA fragmentation of PHA- stimulated T lymphocytes , only a large fragment of DNA map was shown in activated virus-infected group, inactivated virus-infected group and negative control group. Conclusion: This study indicates that the mechanism by which influenza virus kills MDCK cells is the apoptosis. Influenza virus can not directly induce apoptosis of PHA-stimulated T lymphocytes.