Discovery of protease inhibitors for potential antivirals against Chikungunya Virus

Authors

• A Eschman
• S Turk
• Y Yin
• A Marques

Abstract

Chikungunya virus (CHIKV) is a mosquito-borne RNA virus that belongs to the family Togaviridae, genus Alphavirus, which has emerged as one of the most important global arboviral threats over the last decade. However, there is no available antiviral drugs or licensed vaccine for CHKIV. CHIKV nsP2 protease play an important role in processing of viral nonstructural polypeptide precursor to release enzymes required for viral replication, thus making it a promising drug target.
The objective of the current study was to identify small molecules that inhibit nsP2 activity. We developed a fluorescence resonance energy transfer (FRET)-based high-throughput screening (HTS) assay using a fluorogenic peptide substrate encompassing one of the endogenous cleavage sites and purified rCHIKV nsP2pro. The assay was minimized into 1536-well plate format with Z’ value >0.8 and CV <10%. Using this assay, we then interrogated NCATS-sourced small moleculelibraries including 9866(8500 unique) compounds .
From the screenings, 250 compounds were selected for follow-up validation and counter-screenings. Specifically,Full-length nsP2 and an additional peptide were employed for follow-up validations, and FRET-based assays for Papain and NS3-4A proteases were utilized ascounter screening assays. Novel compounds were identified to be potential nsP2 inhibitors andmolecular docking analyses were performed to explain the binding mode of selected compounds. These hits constitute good candidates for testing in cell-based live-virus assay.

Scientific Focus Area: Chemical Biology

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