Nucleotide analogue bemnifosbuvir inhibits hepatitis E virus replication in preclinical models

BACKGROUND: Hepatitis E virus (HEV) infections remain a global health concern. Immunocompromised patients are at an increased risk of developing chronic HEV infection and thereby severe liver disease. Current off-label regimens are suboptimal with treatment failure being reported. Therefore, there is an urgent need for an effective anti-HEV treatment. OBJECTIVE: In this study, we aimed to identify potent inhibitors of HEV replication. DESIGN: We developed a rapid, image-based screening platform based on a full-length HEV fluorescence reporter virus and screened a nucleotide/nucleoside analogue library. The identified lead candidate was validated in authentic hepatocyte culture systems, as well as in a gerbil infection model. RESULTS: Bemnifosbuvir (BEM), previously characterised as a nucleotide analogue with activity against other RNA viruses, efficiently suppressed HEV replication in vitro and in vivo in a dose-dependent manner, with minimal cytotoxicity at effective concentrations. Combining BEM with ribavirin, the off-label drug given to patients with chronic HEV, resulted in an additive antiviral effect against HEV. We found that HEV-3 remains susceptible to inhibition by BEM over an extended treatment period, reducing concerns about the rapid development of viral resistance. Importantly, BEM significantly reduced HEV viral loads and liver inflammation in a gerbil infection model. CONCLUSIONS: Given BEM's favourable safety profile in preclinical and clinical settings, our results suggest investigating its efficacy in patients with chronic HEV infection.