Synergistic drug combination effectively blocks Ebola virus infection

Wei Sun,Shihua He,Carles Martínez-Romero,Jennifer Kouznetsova,Gregory Tawa,Miao Xu,Paul Shinn,Ethan G Fisher,Yan Long,Omid Motabar,Shu Yang,Philip E Sanderson,Peter R Williamson,Adolfo García-Sastre,Xiangguo Qiu,Wei Zheng

doi:10.1016/j.antiviral.2016.11.017

Abstract

Although a group of FDA-approved drugs were previously identified with activity against Ebola virus (EBOV), most of them are not clinically useful because their human blood concentrations are not high enough to inhibit EBOV infection. We screened 795 unique three-drug combinations in an EBOV entry assay. Two sets of three-drug combinations, toremifene-mefloquine-posaconazole and toremifene-clarithromycin-posaconazole, were identified that effectively blocked EBOV entry and were further validated for inhibition of live EBOV infection. The individual drug concentrations in the combinations were reduced to clinically relevant levels. We identified mechanisms of action of these drugs: functional inhibitions of Niemann–Pick C1, acid sphingomyelinase, and lysosomal calcium release. Our findings identify the drug combinations with potential to treat EBOV infection.

Highlights

The EBOV entry pathway has been extensively studied (Jae and Brummelkamp, 2015; Moller-Tank and Maury, 2015), a few components involved at the early and the late stages are still unknown
We hypothesize that a combination therapy of three-drugs with different mechanisms of action will be able to block EBOV infection with lower individual drug concentrations due to the synergistic effect
To increase the screening throughput for large numbers of three-drug combinations, we fixed two drugs at concentrations below their human Cmax and varied concentrations of the third drug by 1:3 dilutions

Summary

Introduction

The EBOV entry pathway has been extensively studied (Jae and Brummelkamp, 2015; Moller-Tank and Maury, 2015), a few components involved at the early and the late stages are still unknown. Involvements of cathepsin B/L (Chandran et al, 2005), Niemann Pick C1 protein (NPC1) (Carette et al, 2011; Cote et al, 2011), acid sphingomyelinase (ASM) (Miller et al, 2012), and two-pore channel (TPC) (Sakurai et al, 2015) in EBOV entry have been reported. The hydrolyzed EBOV GP binds to NPC1 activating lysosome escape and virus genome injection to cytoplasm where viral replication occurs. Fibroblasts derived from patients deficient in NPC1 and NPC1 knock-out mice showed resistance to EBOV infection (Herbert et al, 2015). Tetrandrine, a small molecule inhibitor of TPCs, showed a moderate protection in the EBOV mouse model (Sakurai et al, 2015)

Methods

Results

Conclusion