Discovery and development of antiviral candidates against the Zika Virus protease NS2B-NS3pro

Abstract

Zika virus (ZIKV) is a flavivirus transmitted by the bite of the Aedes aegypti mosquito, responsible for outbreaks of Zika fever, which remains with the potential to generate major global public health impacts. In 2015/16, the virus caused a major outbreak in Brazil, resulting in several cases of congenital Zika syndrome in fetuses and newborns of infected mothers and Guillain-Barré syndrome in adults. Despite this, the management of ZIKV is done entirely by controlling the mosquito vector and treatment of symptoms, as there are no drugs or vaccines available. Therefore, is crucial the continuity of efforts to find a safe and effective treatment. One of the most efficient methods of discovering new antivirals is through high-throughput screening (HTS) of large libraries of molecules in search of specific inhibitors, among which viral proteases are an important target. The ZIKV genome is translated into a single polyprotein, which is cleaved by the ZIKV NS2B-NS3 protease complex (NS2B-NS3pro) in a reaction that can be reproduced in the laboratory by enzymatic assays based on the cleavage of fluorescent substrates. In this project, expression and purification of the recombinant ZIKV protease will be performed to use it as a target for large molecule library screening and fragment screening. Inhibition of the enzyme will be validated in cellular assays with subgenomic replicon and aspects of the interaction between the protease and ligands will be elucidated through crystallographic assays. Based on the binding mode of potential inhibitors, structural modifications will be proposed to optimize antiviral potency and selectivity. The project is linked to FAPESP's CEPID CIBFar (Case 2013/07600-3) and will be a continuation and deepening of the candidate's Scientific Initiation project in search for anti-ZIKV agents (FAPESP Case No.: 2021/01686-0). (AU)