Establishment of enterically transmitted hepatitis virus animal models using lipid nanoparticle-based full-length viral genome RNA delivery system.

Background: Enterically transmitted hepatitis viruses, such as hepatitis A virus (HAV) and hepatitis E virus (HEV), remain notable threats to public health. However, stable and reliable animal models of HAV and HEV infection are lacking.

Objective: This study aimed to establish HAV and HEV infections in multiple small animals by intravenously injecting lipid nanoparticle (LNP)-encapsulated full-length viral RNAs (LNP-vRNA).

Design: In vitro transcribed and capped full-length HAV RNA was encapsulated into LNP and was intravenously inoculated to -/- mice, and HEV RNA to rabbits and gerbils. Virological parameters were determined by RT-qPCR, ELISA and immunohistochemistry. Liver histopathological changes were analysed by H&E staining. Antiviral drug and vaccine efficacy were further evaluated by using the LNP-vRNA-based animal model.

Results: On intravenous injection of LNP-vRNA, stable viral shedding was detected in the faeces and infectious HAV or HEV was recovered from the livers of the inoculated animals. Liver damage was observed in LNP-vRNA (HAV)-injected mice and LNP-vRNA (HEV)-injected rabbits. Mongolian gerbils were also susceptible to LNP-vRNA (HEV) injections. Finally, the antiviral countermeasures and in vivo function of HEV genome deletions were validated in the LNP-vRNA-based animal model.

Conclusion: This stable and standardised LNP-vRNA-based animal model provides a powerful platform to investigate the pathogenesis and evaluate countermeasures for enterically transmitted hepatitis viruses and can be further expanded to other viruses that are not easily cultured in vitro or in vivo.