Evaluation of anti-Zika virus activities of broad-spectrum antivirals and NIH clinical collection compounds using a cell-based, high-throughput screen assay

Antiviral Res. 2017 Feb:138:47-56. doi: 10.1016/j.antiviral.2016.11.018. Epub 2016 Dec 3.

Abstract

Recent studies have clearly underscored the association between Zika virus (ZIKV) and severe neurological diseases such as microcephaly and Guillain-Barre syndrome. Given the historical complacency surrounding this virus, however, no significant antiviral screenings have been performed to specifically target ZIKV. As a result, there is an urgent need for a validated screening method and strategy that is focused on highlighting potential anti-ZIKV inhibitors that can be further advanced via rigorous validation and optimization. To address this critical gap, we sought to test whether a cell-based assay that measures protection from the ZIKV-induced cytopathic effect could serve as a high-throughput screen assay for discovering novel anti-ZIKV inhibitors. Employing this approach, we tested the anti-ZIKV activity of previously known broad-spectrum antiviral compounds and discovered several compounds (e.g., NITD008, SaliPhe, and CID 91632869) with anti-ZIKV activity. Interestingly, while GTP synthesis inhibitors (e.g., ribavirin or mycophenolic acid) were too toxic or showed no anti-ZIKV activity (EC50 > 50 μM), ZIKV was highly susceptible to pyrimidine synthesis inhibitors (e.g., brequinar) in the assay. We amended the assay into a high-throughput screen (HTS)-compatible 384-well format and then screened the NIH Clinical Compound Collection library, which includes a total of 727 compounds organized, using an 8-point dose response format with two Zika virus strains (MR766 and PRVABC59, a recent human isolate). The screen discovered 6-azauridine and finasteride as potential anti-ZIKV inhibitors with EC50 levels of 3.18 and 9.85 μM for MR766, respectively. We further characterized the anti-ZIKV activity of 6-azauridine and several pyrimidine synthesis inhibitors such as brequinar in various secondary assays including an antiviral spectrum test within flaviviruses and alphaviruses, Western blot (protein), real-time PCR (RNA), and plaque reduction assays (progeny virus). From these assays, we discovered that brequinar has potent anti-ZIKV activity. Our results show that a broad anti-ZIKV screen of compound libraries with our CPE-based HTS assay will reveal multiple chemotypes that could be pursued as lead compounds for therapies to treat ZIKV-associated diseases or as molecular probes to study the biology of the ZIKV replication mechanism.

Publication types

  • Evaluation Study

MeSH terms

  • Animals
  • Antiviral Agents / pharmacology*
  • Azauridine / pharmacology
  • Biphenyl Compounds / pharmacology
  • Chlorocebus aethiops
  • Cytopathogenic Effect, Viral / drug effects
  • Drug Discovery*
  • High-Throughput Screening Assays / methods
  • Humans
  • Ribavirin / pharmacology
  • Small Molecule Libraries*
  • Vero Cells
  • Virus Replication / drug effects
  • Zika Virus / drug effects*
  • Zika Virus Infection / virology

Substances

  • Antiviral Agents
  • Biphenyl Compounds
  • Small Molecule Libraries
  • Ribavirin
  • brequinar
  • Azauridine