Tanomastat exerts multi-targeted inhibitory effects on viral capsid dissociation and RNA replication in human enterovirusesResearch in context
Therese Yien May Lim,
Chaitanya K. Jaladanki,
Yi Hao Wong,
Thinesshwary Yogarajah,
Hao Fan,
Justin Jang Hann Chu
Affiliations
Therese Yien May Lim
Laboratory of Molecular RNA Virology and Antiviral Strategies, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
Chaitanya K. Jaladanki
Bioinformatics Institute, Agency for Science, Technology and Research (A∗STAR), 30 Biopolis Street, Matrix #07-01, 138671, Singapore
Yi Hao Wong
NUSMed Biosafety Level 3 Core Facility, Yong Loo Lin School of Medicine, National University of Singapore, 14 Medical Drive, 117599, Singapore
Thinesshwary Yogarajah
Laboratory of Molecular RNA Virology and Antiviral Strategies, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Infectious Disease Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, 117597, Singapore; Corresponding author. Laboratory of Molecular RNA Virology and Antiviral Strategies, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
Hao Fan
Bioinformatics Institute, Agency for Science, Technology and Research (A∗STAR), 30 Biopolis Street, Matrix #07-01, 138671, Singapore; Synthetic Biology Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Drive, 117597, Singapore; Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Medical Drive, 117596, Singapore; Duke-NUS Medical School, 8 College Rd, 169857, Singapore; Corresponding author. Bioinformatics Institute, Agency for Science, Technology and Research (A∗STAR), 30 Biopolis Street, Matrix #07-01, 138671, Singapore.
Justin Jang Hann Chu
Laboratory of Molecular RNA Virology and Antiviral Strategies, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; NUSMed Biosafety Level 3 Core Facility, Yong Loo Lin School of Medicine, National University of Singapore, 14 Medical Drive, 117599, Singapore; Infectious Disease Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, 117597, Singapore; Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A∗STAR), 61 Biopolis Drive, Proteos #06-05, 138673, Singapore; Corresponding author. Laboratory of Molecular RNA Virology and Antiviral Strategies, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
Summary: Background: Global cyclical outbreaks of human enterovirus infections has positioned human enterovirus A71 (EV-A71) as a neurotropic virus of clinical importance. However, there remains a scarcity of internationally approved antivirals and vaccines. Methods: In pursuit of repurposing drugs for combating human enteroviruses, we employed a comprehensive pharmacophore- and molecular docking-based virtual screen targeting EV-A71 capsid protein VP1-4, 3C protease, and 3D polymerase proteins. Among 15 shortlisted ligand candidates, we dissected the inhibitory mechanism of Tanomastat in cell-based studies and evaluated its in vivo efficacy in an EV-A71-infected murine model. Findings: We demonstrated that Tanomastat exerts dose-dependent inhibition on EV-A71 replication, with comparable efficacy profiles in enterovirus species A, B, C, and D in vitro. Time-course studies suggested that Tanomastat predominantly disrupts early process(es) of the EV-A71 replication cycle. Mechanistically, live virus particle tracking and docking predictions revealed that Tanomastat specifically impedes viral capsid dissociation, potentially via VP1 hydrophobic pocket binding. Bypassing its inhibition on entry stages, we utilized EV-A71 replication-competent, 3Dpol replication-defective, and bicistronic IRES reporter replicons to show that Tanomastat also inhibits viral RNA replication, but not viral IRES translation. We further showed that orally administered Tanomastat achieved 85% protective therapeutic effect and alleviated clinical symptoms in EV-A71-infected neonatal mice. Interpretation: Our study establishes Tanomastat as a broad-spectrum anti-enterovirus candidate with promising pre-clinical efficacy, warranting further testing for potential therapeutic application. Funding: MOE Tier 2 grants (MOE-T2EP30221-0005, R571-000-068-592, R571-000-076-515, R571-000-074-733) and A∗STAR Biomedical Research Council (BMRC).
