Generation of a Bactrian camel hepatitis E virus by a reverse genetics system

Area of Science:

• Virology
• Hepatitis E Virus Research
• Zoonotic Disease Studies

Background:

• Bactrian camel hepatitis E virus (HEV-8) is a novel genotype 8 HEV with zoonotic potential, identified in the *Orthohepevirus A* species.
• Previous research lacked a cell-culture or reverse genetics system for HEV-8, hindering studies on its replication and pathogenesis.
• HEV-8 has demonstrated cross-transmission to cynomolgus monkeys, highlighting a potential risk for human infection.

Purpose of the Study:

• To establish a cell-culture system for the replication of HEV-8.
• To generate replication-competent HEV-8 using a reverse genetics approach.
• To investigate the potential for zoonotic transmission and identify therapeutic candidates for HEV-8 infection.

Main Methods:

• Synthesized capped genomic HEV-8 RNAs via *in vitro* transcription.
• Transfected PLC/PRF/5 cells with the synthesized HEV-8 RNAs to recover and passage the virus (HEV-8M2 strain).
• Assessed viral replication in various cell lines (PLC/PRF/5, A549, Caco-2, HepG2 C3/A, Vero, Hela S3, HEp-2C, 293T, GL37) and animal models (cynomolgus monkeys, nude rats, BALB/c nude mice).
• Evaluated the efficacy of antiviral drugs (ribavirin, favipiravir) against HEV-8 replication.

Main Results:

• Successfully established a cell-culture system for HEV-8 replication using PLC/PRF/5 cells; A549 and Caco-2 cells also supported replication.
• Recovered and passaged the replication-competent HEV-8M2 strain, confirming the functionality of the reverse genetics system.
• Demonstrated HEV-8M2 infectivity in cynomolgus monkeys, reinforcing its zoonotic risk, but not in nude rats or mice.
• Found that ribavirin efficiently inhibited HEV-8M2 replication, while favipiravir showed no effect.

Conclusions:

• A functional cell-culture and reverse genetics system for HEV-8 has been established, enabling further research into its biology.
• HEV-8 poses a zoonotic risk, as evidenced by its infectivity in cynomolgus monkeys.
• Ribavirin is a potential therapeutic agent for treating HEV-8-induced hepatitis.