Influenza A virus infection causes acute respiratory syndrome and leads to sometimes lethal diseases includ ing pneumonia. Identifying host factors involved in pathogenesis is important for the prevention and treatment of influenza. Type I interferons (IFNs) are essential to activating antiviral responses against influenza A virus. We show that the viral polymerase complex inhibited IFNβ promoter activation. Moreover, PB 2 inhibited the transcription of endogenous IFNβ gene induced after influenza A virus infection. The viral polymerase is critical for regulating host anti-viral response through binding to IPS-1 and inhibition of IFNβ production.
We also demonstrated that Siva-1 is crucial for apoptosis induction by influenza A virus and is involved in its viral replication. Expression of Siva-1 enhanced apoptosis induction after influenza A virus infection and knockdown of Siva-1 expression strongly inhibited it. Furthermore, the replication of influenza A virus was significantly suppressed by Siva-1 knockdown.
Recently, we examined the inhibitory effects of some herbal medicines on influenza A virus replication. Ex tracts of gingyosan and maoto had inhibitory effects for the replication of influenza A viruses. We analyzed the effect of fractions of these extracts and analyzed the main ingredients with a HPLC system.