Discovery And Activity Characterization Of Zika Virus NS5 RdRp Inhibitor

Zika virus(ZIKV)is a member of the Flaviviridae family,transmitting through mosquitoes,sex intercourse or vertical transmission from mother to fetus.The pandemic of ZIKV in Americas infected more than 700,000 people between 2015 and 2016,leading to numerous cases of neuroimmune disease in adults and fetal microcephaly in pregnant women.Concerning a global health crisis,WHO declared ZIKV a Public Health Emergency of International Concern.There are currently no approved vaccines or drugs for ZIKV infection.ZIKV is a single-stranded positive-sense RNA,encoding a polyprotein of three structural proteins(E,C and prM)and seven non-structural proteins(NS1,NS2A,NS2B,NS3,NS4A,NS4B and NS5).Since NS5 RdRp plays an important role in replication and transcription of ZIKV and is absent in human beings,it is proposed a potential drug target for anti-ZIKV agents.In this work,we screened 935 compounds against RdRp via LibDcok from an antiinfection compound library and a natural product library,and 11 compounds showing the top 11 LibDock scores were selected.These were further tested by RdRp enzymatic inhibition,cytotoxicity evaluation and affinity analysis.Finally,we found that Posaconazole(POS)had a good inhibitory effect on RdRp with an IC50 of 4.29 μM and no significant toxic effect with CC50=101 μM.The results of surface plasmon resonance reaction showed that POS was able to bind directly to RdRp with good affinity(KD=2.76×10-5 M).D666 was identified as the key amino in the reaction between POS and RdRp by molecular docking and surface plasmon resonance assay.Finally,POS showed good anti-ZIKV activity in antiviral assays with an EC50 value of 0.59 μM.In conclusion,POS,an inhibitor of ZIKV NS5 RdRp,was identified by virtual screening and biological assays.Further experiments revealed that POS inhibited RdRp activity by binding with the key amino acid D666 and exhibited potent anti-ZIKV activity.Our reaserch might provide the lead compound to anti-ZIKV drugs.Moreover,the combination of virtual screening and biological assays is an important tool in anti-infective drugs development,which can improve the hit rate of candidate compounds and save cost and time of screening.