Discovery of Zika virus therapeutics using a replicon assay

ABSTRACT The Zika virusZIKVis the cause of an explosive pandemic of infections across South and Central Americathe Caribbeanand the southeastern region of the United StatesZIKV is a flavivirusa family of small positive strand RNA viruses that includes Dengue virusDENVWest Nile virusWNVYellow fever virusYFVand hepatitis C virusHCVZIKV is transmitted to humans by mosquitoes of the Aedes genusFor the most partZIKV causes mild symptoms that mimic dengue feverhoweverZIKV infections in the Americas have been associated with congenital microcephaly and to the neurotropic Guillain BarrsyndromeThis prompted the World Health Organization to declare ZIKV to be apublic health emergency of international concernDespite the significant medical need for prophylactic or therapeutic treatmentsthere are no vaccines or drugs that have been approved for ZIKVThereforenovel therapeutic agents for prophylaxis or treatment of acute ZIKV infections are neededTo address this significant unmet medical needwe will utilize a stable ZIKV replicon cell line to carry out a high throughput screen to identify novel inhibitors of ZIKV replicationwhich will be developed into drugs for ZIKV infectionsOur approach is based on the strong scientific premise that is built on the longstanding success of flavivirus replicons in drug discovery and developmentRecentlythe laboratory of our collaborator Pei Yong ShiUniversity of Texas Medical Branchreported the construction and validation of a ZIKV replicon cell lineZIKV Rep neoIn preliminary studieswe have used the ZIKV Rep neo cell line to successfully carry out a small scale screen of FDA approve compoundsdemonstrating the feasibility of our approachIn Phase Iwe will apply the ZIKV replicon assay to screen a library ofsmall molecules for compounds that inhibit replicationand will use counter screens and PAINS filters to eliminate non specific inhibitors and cytotoxic compoundsWe will prioritize the hits based on the results of a panel of secondary assays to assess the potency against infectious ZIKVspectrum of activity against flavivirusescytotoxicityand the drug like properties of these compoundsThe mechanism of action of prioritized compounds will be investigated to verify that prioritized hits target viral proteinsand preliminary structure activity relationships will be assessedInhibitors that meet the stringent criteria listed in the milestones for each specific aim will undergo hit to lead optimization in a subsequent Phase II projectIn Phase I of this project we will accomplish the following Specific AimsAimIdentify potent inhibitors of the ZIKV replicon in a high throughput screenAimPrioritize confirmed hits based on potencyspecificityand drug like propertiesAimDetermine the mechanism of action of prioritized inhibitorsAimEstablish preliminary structure activity relationships for prioritized inhibitors PROJECT NARRATIVE The Zika virusZIKVis the cause of an explosive pandemic of infections across South and Central Americathe Caribbeanand the southeastern region of the United StatesZIKV infections in the Americas have been associated with congenital microcephaly and to the neurotropic Guillain Barrsyndromewhich prompted the World Health Organization to declare ZIKV to be apublic health emergency of international concernDespite the significant medical need for prophylactic or therapeutic treatmentsthere are no vaccines or drugs that have been approved for ZIKVTo address this significant unmet medical needwe will utilize a stable ZIKV replicon cell line to carry out a high throughput screen to identify novel inhibitors of ZIKV replicationwhich will be developed into drugs to prevent or treat ZIKV infections