Lifecycle modelling systems support inosine monophosphate dehydrogenase (IMPDH) as a pro-viral factor and antiviral target for New World arenaviruses.

Infection with Junín virus (JUNV) is currently being effectively managed in the endemic region using a combination of targeted vaccination and plasma therapy. However, the long-term sustainability of plasma therapy is unclear and similar resources are not available for other New World arenaviruses. As a result, there has been renewed interest regarding the potential of drug-based therapies. To facilitate work on this issue, we present the establishment and subsequent optimization of a JUNV minigenome system to a degree suitable for high-throughput miniaturization, thereby providing a screening platform focused solely on factors affecting RNA synthesis. Using this tool, we conducted a limited drug library screen and identified AVN-944, a non-competitive inosine monophosphate dehydrogenase (IMPDH) inhibitor, as an inhibitor of arenavirus RNA synthesis. We further developed a transcription and replication competent virus-like particle (trVLP) system based on these minigenomes and used it to screen siRNAs against IMPDH, verifying its role in supporting arenavirus RNA synthesis. The antiviral effect of AVN-944, as well as siRNA inhibition, on JUNV RNA synthesis supports that, despite playing only a minor role in the activity of ribavirin, exclusive IMPDH inhibitors may indeed have significant therapeutic potential for use against New World arenaviruses. Finally, we confirmed that AVN-944 is also active against arenavirus infection in cell culture, supporting the suitability of arenavirus lifecycle modelling systems as tools for the screening and identification, as well as the mechanistic characterization, of novel antiviral compounds.

Novel Arenavirus Entry Inhibitors Discovered by Using a Minigenome Rescue System for High-Throughput Drug Screening.

UNLABELLED: Certain members of the Arenaviridae family are category A agents capable of causing severe hemorrhagic fevers in humans. Specific antiviral treatments do not exist, and the only commonly used drug, ribavirin, has limited efficacy and can cause severe side effects. The discovery and development of new antivirals are inhibited by the biohazardous nature of the viruses, making them a relatively poorly understood group of human pathogens. We therefore adapted a reverse-genetics minigenome (MG) rescue system based on Junin virus, the causative agent of Argentine hemorrhagic fever, for high-throughput screening (HTS). The MG rescue system recapitulates all stages of the virus life cycle and enables screening of small-molecule libraries under biosafety containment level 2 (BSL2) conditions. The HTS resulted in the identification of four candidate compounds with potent activity against a broad panel of arenaviruses, three of which were completely novel. The target for all 4 compounds was the stage of viral entry, which positions the compounds as potentially important leads for future development. IMPORTANCE: The arenavirus family includes several members that are highly pathogenic, causing acute viral hemorrhagic fevers with high mortality rates. No specific effective treatments exist, and although a vaccine is available for Junin virus, the causative agent of Argentine hemorrhagic fever, it is licensed for use only in areas where Argentine hemorrhagic fever is endemic. For these reasons, it is important to identify specific compounds that could be developed as antivirals against these deadly viruses.