Cryo-EM structures of Nipah virus polymerases and high-throughput RdRp assay development enable anti-NiV drug discovery.

Summary

This mechanistic study defines structural features of the NiV L-P polymerase complex across strains and uncovers a back-priming activity. Complementary high-sensitive and high-throughput polymerase assays were established to accelerate screening of direct-acting antivirals against henipaviruses.

Key Findings

• Resolved multiple cryo-EM structures of full-length and truncated NiV polymerases from Malaysia and Bangladesh strains.
• Identified two conserved loops within the L protein PRNTase domain and interactions between RdRp-PRNTase and CD domains.
• Discovered a back-priming activity of the NiV polymerase using a highly sensitive radiolabeled RNA synthesis assay.
• Developed fluorescence and luminescence-based non-radioactive polymerase assays suitable for high-throughput screening of L inhibitors.

Clinical Implications

While preclinical, these assays and structural insights enable rational screening and optimization of polymerase inhibitors, potentially expediting candidate selection for future in vivo and clinical studies.

Limitations

• Findings are limited to in vitro structural and biochemical systems without in vivo validation.
• No efficacy data for specific antiviral compounds in cellular or animal models were reported.

Future Directions

Apply the assays to high-throughput library screening, followed by medicinal chemistry optimization and in vivo efficacy/toxicity studies against henipavirus infection.