Screening drug libraries to discover virus-directed or host-directed therapy for EV-A71 infection

The MMV Pandemic Response Box drug library contains a chemically and pharmacologically diverse mixture of early-stage, emerging anti-infective scaffolds, and mature compounds currently undergoing clinical development. It is an assembly of 153 antiviral agents, 201 antibacterial, and 46 antifungal compounds. In this thesis, only 153 antiviral agents were used for screening enterovirus A71 (EV-A71) inhibitors. It was hypothesized that the antiviral agents contained in the Pandemic Response Box might have compounds that bind and interfere with target molecules or cellular pathways that are conserved or shared among the closely related viruses with the EV-A71. This thesis aimed to screen antiviral agents included in the Pandemic Response Box for repurposing to anti-EV-A71 activity and investigate the inhibitory effects of the compounds on viral replication. Seven compounds were found to have negligible cytotoxicity cells and the ability to rescue the infected cells. The hit compounds were verified for anti-EV-A71 activity by virus reduction assays for viral RNA copy numbers, viral protein synthesis, and mature particle production using qRT-PCR, Western blot analysis, and CCID50 assay, respectively. Some of the hit compounds could reduce EV-A71 genome replication and protein synthesis. It was found that D-D7 (2-pyridone-containing human rhinovirus 3C protease inhibitor) exhibited the highest anti-EV-A71 activity. The 2-pyridone-containing human rhinovirus 3C protease inhibitor could be repurposed as an anti-EV-A71 agent by targeting a conserved substrate-binding motif of the enzyme.