Related Experiment Video

Updated: Aug 22, 2026

A Semi-Quantitative Drug Affinity Responsive Target Stability (DARTS) assay for studying Rapamycin/mTOR interaction
05:28

A Semi-Quantitative Drug Affinity Responsive Target Stability (DARTS) assay for studying Rapamycin/mTOR interaction

Published on: August 27, 2019

In vitro antiviral effects of an mTORC1 inhibitor targeting the rapamycin-binding protein complex

Takafumi Yamada1, Ryosuke Matsuura2, Sonoko Watanuki2

  • 1Laboratory of Global Infectious Diseases Control Science, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.

Microbial Pathogenesis
|August 20, 2026
PubMed

Insights

A novel drug, WRX606, effectively inhibits viral replication by targeting the host factor mTORC1. This broad-spectrum antiviral shows promise against influenza and coronaviruses, offering a new strategy against mutable viral pathogens.

Area of Science:

  • Virology
  • Drug Discovery
  • Cellular Metabolism

Background:

  • Mutable viral pathogens necessitate broad-spectrum antiviral drugs targeting stable host factors for a high genetic barrier to resistance.
  • The mammalian target of rapamycin complex 1 (mTORC1) is a critical metabolic regulator co-opted by viruses for protein translation.
  • Developing novel inhibitors of mTORC1 is crucial for antiviral therapeutic strategies.

Purpose of the Study:

  • To evaluate the novel mTORC1 inhibitor WRX606 as a broad-spectrum antiviral agent against representative RNA viruses.
  • To assess the cytotoxicity and antiviral potency of WRX606.
  • To elucidate the mechanism of action of WRX606 against viral replication.

Main Methods:

  • Cytotoxicity assays were performed across multiple cell lines (MRC-5, HeLa, COS-1, MDCK) to determine CC50 values.
  • Antiviral activity was assessed against Influenza A virus and human coronavirus 229E using plaque assays and cell viability measurements (WS8, CPE).
  • Mechanistic studies involved RT-qPCR, western blotting, and time-of-addition assays to investigate viral adsorption, genome replication, protein translation, and virion release.

Main Results:

  • WRX606 exhibited low cytotoxicity with CC50 values > 40 μM across tested cell lines.
  • The compound potently inhibited Influenza A virus (IC50 = 13.0-32.0 nM) and human coronavirus 229E replication, with high selectivity indices.
  • WRX606 did not affect viral adsorption or genome replication but interfered with viral structural protein translation/stability, reducing progeny virion release.

Conclusions:

  • WRX606 is a potent, broad-spectrum antiviral agent with low cytotoxicity, targeting the host factor mTORC1.
  • WRX606 represents a promising host-directed therapeutic strategy against RNA viruses like influenza and coronaviruses.
  • The drug's mechanism involves inhibiting viral protein translation or stability, crucial for progeny virion production and release.
Keywords:
Broad-spectrum antiviral agentHost-directed therapyHuman coronavirusInfluenza virusMammalian target of rapamycin complex 1 inhibitorViral translation inhibition

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