Development of a high‐throughput screening assay to identify equine virus arteritis replication inhibitors

International audienceBackground: During the last 60 years, the equine arteritis virus (EAV) has induced respiratory and reproductive problems in equids after infection. EAV is a significant problem for horse breeders and the equine industry. Despite two vaccines being available in the market, the current vaccination coverage remains insufficient to prevent global outbreaks. Recently our laboratory identified the first commercial antiviral molecule that impairs EAV replication. Unfortunately, it is only approved for use in humans and small animals. This proof of concept suggests that other antiviral molecules should exist and may be approved for use in large animals.Objective: This project aims to screen thousands of antiviral molecules to find those that impair EAV replication.Study design: In vitro study.Methods: To test thousands of molecules, a high-throughput screening (HTS) model based on ATP quantification was developed, which allows evaluation of the cytotoxicity and cellular protection of molecules. In addition, the EAV replication was measured by analysing the culture supernatants by RT-qPCR.Results: The HTS system allowed screening of 1250 molecules from 2 chemical libraries. The results showed that 75/1250 molecules induced cellular protection after 72 hpi. Regarding the EAV replication, 64 molecules impaired EAV replication efficiently and 3/64 molecules showed an antiviral capacity for the first time.Main limitations: In vitro models may not mimic the in vivo effects.Conclusions: The promising molecules will require in vivo testing in horses and, if effective, have the potential to thus complement EVA vaccines to better control EVA outbreaks and limit viral dissemination