Epigallocatechin-3-gallate Exhibits Antiviral Effects Against The Duck Tembusu Virus Via Blocking Virus Entry And Upregulating Type Ⅰ Interferons

The duck Tembusu virus（DTMUV）is a new flavivirus transmitted by mosquitoes that caused massive economic losses in Southeast Asian countries and China’s poultry sectors.To date,no antiviral medications have been reported to be effective against this virus.Green tea polyphenol（-）Epigallocatechin-3-gallate（EGCG）is the major catechin component of green tea（Cameria sinensis）,and is known to possess antiviral activities against a wide range of DNA viruses and RNA viruses.However,whether EGCG can prevent DTMUV infection is uncertain.The purposes of current research were to investigate the anti-DTMUV activity and mechanism of action of EGCG both in vitro and in vivo.Numerous,EGCG treatment processes were applied to investigate EGCG’s broad antiviral activity in a BHK-21 cells infected with DTMUV.Virus titers were evaluated in mock and in infected cell cultures treated with EGCG using the TCID₅₀and DTMUV mRNA copy number was assessed using q RT-PCR.Additionally,In DTMUV infected ducklings,the therapeutic efficacy of EGCG was tested.Our results revealed that treated with different concentration of EGCG viral titers,viral copy number,and expression of viral E protein significantly decreased in BHK-21 cells.In addition,we reported that EGCG showed direct antiviral activity against DTMUV.Notably,the efficacy of the virus to bind to the surface was significantly reduced,demonstrating that EGCG inhibits the viral adsorption process significantly.Replication of DTMUV was also suppressed in EGCG treated BHK21 cells following virus entry,probably due to higher levels of interferonαandβ.Finally,in a duckling infection model,EGCG was found to be effective against DTMUV,where the rate of survival has significantly increased.This study demonstrates for the first time that EGCG protects from DTMUV,implying that it has an antiviral activity.