The Development And Mechanism Of A Novel Broad Spectrum Anti-coronavirus Inhibitor

Coronaviruses(CoVs)are enveloped single-stranded positive-sense RNA viruses in the family Coronaviridae,which own the largest known genome approximately 27?31.5 kb in length among all the RNA viruses.The Coronaviridae subfamily has been divided into four genera named Alphacoronvirus(?CoV),Betacoronavirus(?CoV),Gammacoronavirus(yCoV)and Deltacoronavirus(?CoV)based on phylogeny.TGEV,HCoV-229E,FCoV and HCoV-NL63 belong to ?CoVs,and pCoVs include HCoV-OC43,MHV,SARS-CoV,HCoV-HKU1 and MERS-CoV,but IBV is a?CoV.Like eukaryotic cellular and many other viral mRNAs,the 5' end of coronaviral RNAs also possess a cap structure which plays vital roles in RNA stability,translation initiation and evading host antiviral response.The RNA cap of coronavirus is made of an N7-methylated guanine nucleotide connected through a 5'-5' triphosphate bridge to the first nucleotide,and this cap-0 structure(7Me GpppA...)is converted into a cap-1 structure(7MeGpppA2'-O-Me…)through 2'-O methylation of the latter.It has been demonstrated that nsp16 has S-adenosyl-L-methionine-dependent 2'-O methyltransferase(2'-OMTase)activity only interacting with nsp10 among all the CoVs except FCoV,but nsp10/16 complex activity of FCoV is much stronger than nsp16 alone.So nsp10/16 complex is a great potential broad-spectrum antiviral drug target.In this study,we design 8 peptides derived from the region of MERS-CoV nsp10 interacting with nspl6 to inhibit its 2'-O MTase activity by competitively binding nsp16 with wild-type nsp10.We find that only P21 or TCP21(the N terminus of P21 fused with a truncated HIV Tat)can inhibit nsp10/16 complex activity of ten Co Vs mentioned above in vitro and the replications of Co Vs in vivo respectively,suggesting that it may be developed a great potential broad-spectrum peptide inhibitor to treat a wide range of CoVs infection.