Identification of broad-spectrum inhibitors against Bunyaviral endonucleases

Authors

• YM Ahn
• S Costmire
• S Ogden
• D Esposito
• S Messing
• K Shamim
• X Hu
• L Ye
• EM Lee
• NJ Martinez

Abstract

Bunyavirales is an order of segmented (-) strand RNA viruses. Several families in the Bunyavirales order, such as Phenuiviridae, Arenaviridae, Nairoviridae, and Hantaviridae, cause viral hemorrhagic fevers or pulmonary disorders for which no effective therapy exists.
These emerging viruses are considered Category A priority pathogens by the National Institutes of Health due to their potential threat to global health.
Bunyavirales share common mechanisms that can be potentially targeted for the development of broad-spectrum antivirals. Like all segmented (-) strand RNA viruses, Bunyavirales rely on their own transcriptional machinery which contains an endonuclease domain that cleaves the 5’RNA cap of host cell mRNAs, a process called “cap-snatching”, to prime viral transcription. The endonuclease domain of Bunyavirals is therefore a promising antiviral target.

To identify small molecules with potential broad spectrum anti-bunyaviral activity, we developed fluorescence-based enzymatic assays for 4 recombinant endonucleases from Rift Valley Fever, La Cross, Punta Toro, and Hantaan viruses. The assays were miniaturized to 1536-well format to support the quantitative-high throughput screening (qHTS) of a total of ~12K compounds from NCATS-sourced libraries. Hits identified from the screen, were subsequently tested for their ability to engage their intended target in high-throughput enzyme complementation assays. High-throughput viral infection assays were also utilized to further characterize inhibitor activity.

Scientific Focus Area: Chemical Biology

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