Project 5 – Pandemic Virus Helicase Inhibitors ABSTRACT The goal of this project is to develop pan-family, antiviral drug candidates targeting the viral helicase of coronavirus and flavivirus. All priority RNA viruses encode a viral helicase domain in their genomes, and they share high similarity in structure and biochemical features. Viral RNA helicase is a critical component of the viral replicase complex and is essential for RNA virus replication. Further, it shows a high sequence homology within the virus family (e.g., 100% identity within SARS2). Consequently, viral RNA helicases can serve as a novel antiviral target for RNA viruses with a high barrier to drug resistance. During the past 10 years, the Chung lab has made significant contributions to the development of antivirals targeting the alphavirus helicase domain (nsP2) and validated viral helicase as druggable for developing potent antivirals. Based on this success, we hypothesize the viral helicase can serve as a valid target for safe and effective antivirals for SARS2 and other priority RNA viruses. Here, we propose a comprehensive antiviral discovery campaign targeting viral helicase with a multi-disciplinary approach combining ultra-high-throughput screening and DNA-Encoded Chemistry Technology followed by a robust hit validation scheme with antiviral testing, structural biology, and biochemical approaches (Aim 1). Further, we propose to advance promising viral helicase inhibitor hits through hit-to-lead development, giving validated leads as drug development candidates with medicinal chemistry paired with AI-based drug design, DMPK studies, and in vivo antiviral efficacy studies (Aim 2). Finally, we will deliver 1-2 orally bioavailable, patentable, druglike IND-enabled small molecules (a development candidate + backup) that are well-suited for translation by a pharma partner (Aim 3). Our proposal is supported by our discovery of a novel hit compound (UNC0379) with an anti-SARS2 activity from a pilot 100,000-compound library screen (Core B). The PI and established team (Chung, virology/PI; Bannister, Med. Chem/deputy; Spicer, uHTS; Luo, structural biology of viral replicase; Raney, helicase biochemistry) synergistically combine antiviral drug discovery (Head-Gordon, Compchem/AI) with excellent core support (Core B and Core C). Our effort will deliver new classes of direct helicase-targeting antiviral agents for SARS2 infection and other high priority viral pathogens.

Project 5 – Pandemic Virus Helicase Inhibitors PROJECT NARRATIVE The discovery of new antivirals exploiting targets other than viral polymerase and viral proteases is a crucial need for effectively combating viral diseases. Despite the high potential of viral helicases as a novel alternative antiviral target, viral helicase has not been fully explored as an antiviral target. We propose to develop antivirals targeting viral helicase to provide effective and complementary therapeutic options for current and future pandemic viruses, including SARS-CoV-2 and flaviviruses such as Zika virus.