High content image-based screening of a protease inhibitor library reveals compounds broadly active against Rift Valley fever virus and other highly pathogenic RNA viruses

Rajini Mudhasani; Krishna P Kota; Cary Retterer; Julie P Tran; Chris A Whitehouse; Sina Bavari

doi:10.1371/journal.pntd.0003095

High content image-based screening of a protease inhibitor library reveals compounds broadly active against Rift Valley fever virus and other highly pathogenic RNA viruses

PLoS Negl Trop Dis. 2014 Aug 21;8(8):e3095. doi: 10.1371/journal.pntd.0003095. eCollection 2014 Aug.

Authors

Rajini Mudhasani¹, Krishna P Kota¹, Cary Retterer¹, Julie P Tran¹, Chris A Whitehouse¹, Sina Bavari¹

Affiliation

¹ Molecular and Translational Sciences Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America.

Abstract

High content image-based screening was developed as an approach to test a protease inhibitor small molecule library for antiviral activity against Rift Valley fever virus (RVFV) and to determine their mechanism of action. RVFV is the causative agent of severe disease of humans and animals throughout Africa and the Arabian Peninsula. Of the 849 compounds screened, 34 compounds exhibited ≥ 50% inhibition against RVFV. All of the hit compounds could be classified into 4 distinct groups based on their unique chemical backbone. Some of the compounds also showed broad antiviral activity against several highly pathogenic RNA viruses including Ebola, Marburg, Venezuela equine encephalitis, and Lassa viruses. Four hit compounds (C795-0925, D011-2120, F694-1532 and G202-0362), which were most active against RVFV and showed broad-spectrum antiviral activity, were selected for further evaluation for their cytotoxicity, dose response profile, and mode of action using classical virological methods and high-content imaging analysis. Time-of-addition assays in RVFV infections suggested that D011-2120 and G202-0362 targeted virus egress, while C795-0925 and F694-1532 inhibited virus replication. We showed that D011-2120 exhibited its antiviral effects by blocking microtubule polymerization, thereby disrupting the Golgi complex and inhibiting viral trafficking to the plasma membrane during virus egress. While G202-0362 also affected virus egress, it appears to do so by a different mechanism, namely by blocking virus budding from the trans Golgi. F694-1532 inhibited viral replication, but also appeared to inhibit overall cellular gene expression. However, G202-0362 and C795-0925 did not alter any of the morphological features that we examined and thus may prove to be good candidates for antiviral drug development. Overall this work demonstrates that high-content image analysis can be used to screen chemical libraries for new antivirals and to determine their mechanism of action and any possible deleterious effects on host cellular biology.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Animals
Chlorocebus aethiops
Ebolavirus
HeLa Cells
Humans
Image Processing, Computer-Assisted / methods*
Protease Inhibitors / pharmacology*
Rift Valley Fever
Rift Valley fever virus / drug effects*
Small Molecule Libraries*
Vero Cells
Virology / methods*

Substances

Protease Inhibitors
Small Molecule Libraries

Grants and funding

This study was supported by funding from the Defense Threat Reduction Agency (DTRA), Joint Science and Technology Office for Chem Bio Defense (JSTO-CBM.THRV.01.10.RD.19) to SB. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.