Protein kinase inhibitor flavopiridol inhibits the replication of influenza virus in vitro

Abstract:

Abstract:［Objective］To investigate the antiviral effect of the flavonoid compound flavopiridol on influenza A virus and explore its antiviral mechanism． ［Methods］The A549 or Madin-Darby canine kidney (MDCK) cells were infected with influenza A virus A/WSN/33 and treated with flavopiridol． The viral proteins were determined by immunolotting and immunofluorescence． The virus titer was measured by plaque assay． To verify whether the activity of host RNA polymerase Ⅱ was affected by flavopiridol，the phosphorylation status of RNA polymerase Ⅱ CTD domain was analyzed by immunoblotting with phosphor-specific antibody． The amount of viral mRNA，vRNA and cRNA was measured by reverse transcription and PCR． ［Results］The amount of viral proteins was significantly decreased and the titer of virus was greatly reduced in cells treated with flavopiridol． Further analysis showed that the phosphorylation of Ser-2 in the heptad repeat of the CTD domain in RNA polymeraseⅡ was decreased in falvopiridol treated cell． This result indicated that the transcription elongation activity of RNA pol II was impaired upon treatment with flavopiridol． Then we found that the amount of viral vRNA was significantly decreased in flavopiridol treated cells while only moderate decrease of mRNA was observed and almost no reduction of cRNA was detected． ［Conclusion］Flavopiridol can greatly suppress the replication of influenza virus． We propose that the inhibition of the transcription elongation activity of host RNA polymeraseⅡ would cause the decrease of viral mRNA transcription．