The Activities Of Tenofovir Disoproxil Fumarate And Tolvaptan Against Zika Virus

Background and Aims:Zika virus(ZIKV)is an arthropod-borne flavivirus,mainly transmitted through Aedes mosquitoes.Symptoms of infections with the ZDKV are mostly mild and self-limited,but ZIKV infection may also cause severe neurological and autoimmune manifestations,such as microcephaly and Guillain-Barre syndrome.Currently,there is no specific vaccine or drug approved to prevent or treat ZIKV infection.With the outbreak and rapid spread of Zika virus in many countries and regions,there is an urgent need to find effective antiviral treatment.It is particularly important to develop anti-ZIKV drugs because the development of anti-ZIKV vaccine hindered by many factors.The aim of this study is to screen out compounds with good anti-ZIKV activity and to access their anti-ZIKV activity in vitro and in vivo and their mechanism of action,so as to lay a foundation for the development of effective anti-ZIKV drugs.Methods:In this study,we chose ribavirin as the positive drug and firstly screen the anti-ZIKV drugs by plaque assay and MTT assay.After the active compound were screened out,we combined with plaque assay,virus yield reduction assay,Western blot and the results of MTT assay to comprehensively evaluate the anti-ZIKV activity of the compounds and confirmed the therapeutic index of the compounds.Finally,the mechanism and antiviral activity vzvo of the active eompound was studied.Results:We screened out tenofovir disoproxil fumarate(TDF)and tovaptan as a novel anti-ZIKV drug with low cytotoxicity by plaque assay and and MTT assay,then their anti-ZIKV activities was studied comprehensively.TDF and tolvaptan are FDA-approved Drugs,we found that they can effectively reduced the formation of plaque after ZIKV infection and their 50%effective concentration(ECS?)in the inhibition of ZIKV strain SZ-WIV01 replication was 27.47±8.07 ?M and 32.78±3.61?M respectively,while the EC50 of ribavirin was 56.01 ± 12.16 ?M as the positive control.In addition,tovaptan also had good activity against ZIKV strain MR766,with an EC50 of 38.60±6.25 ?M.Further evaluation of the anti-ZIKV activity of TDF and tovaptan showed that TDF and tovaptan also exhibited good anti-ZIKV activity at RNA level and protein level.They not only significantly inhibited ZIKV RNA replication at RNA level,but also significantly inhibited the expression of ZDKV NS2B protein at protein level.The results of MTT assay show that the cytotoxicity of TDF,tolvaptan and ribavirin on Vero cells were very low and the 50%cytotoxic concentration(CC50)values of TDF and ribavirin were all greater than 500 ?M.The CC50 value of tolvaptan was greater than 2000 The therapeutic index of TDF and tovaptan calculated by CC50/EC50 was significantly higher than that of ribavirin.After the study of the anti-ZIKV mechanism of tovaptan,it was found that tovaptan did not exert its anti-ZIKV effect through selective antagonism of vasopressin-2 receptor(V2R),suggesting that tovaptan may exert its anti-ZIKV effect through a new mechanism.The time of drug addition assay shown that tovaptan inhibited post-entiy events during the ZIKV replication cycle rather than at the virus adsorption and entry stage.Study on the anti-ZIKV activity of tovaptan in vivo exhibited that tovaptan could significantly reduce the death of mice infected with ZIKV.Conclusions:TDF and tolvaptan were found to have anti-ZIKV activity for the first time in our study.Their inhibitory effects on ZIKV were significantly better than ribavirin,and they are expected to be candidate drugs for anti-ZIKV infection.