Hepatitis E Virus (HEV) Genotype 3 Infection of Human Liver Chimeric Mice as a Model for Chronic HEV Infection

Genotype 3 (gt3) hepatitis E virus (HEV) infections are emerging in Western countries. Immunosuppressed patients are at risk of chronic HEV infection and progressive liver damage, but no adequate model system currently mimics this disease course. Here we explore the possibilities of in vivo HEV studies in a human liver chimeric mouse model (uPA(+/+) Nod-SCID-IL2R gamma(-/-)) next to the A549 cell culture system, using HEV RNA-positive EDTA-plasma, feces, or liver biopsy specimens from 8 immuno-compromised patients with chronic gt3 HEV. HEV from feces-or liver-derived inocula showed clear virus propagation within 2 weeks after inoculation onto A549 cells, compared to slow or no HEV propagation of HEV RNA-positive, EDTA-plasma samples. These in vitro HEV infectivity differences were mirrored in human-liver chimeric mice after intravenous (i.v.) inoculation of selected samples. HEV RNA levels of up to 8 log IU HEV RNA/gram were consistently present in 100% of chimeric mouse livers from week 2 to week 14 after inoculation with human feces-or liver-derived HEV. Feces and bile of infected mice contained moderate to large amounts of HEV RNA, while HEV viremia was low and inconsistently detected. Mouse-passaged HEV could subsequently be propagated for up to 100 days in vitro. In contrast, cell culture-derived or seronegative EDTA-plasma-derived HEV was not infectious in inoculated animals. In conclusion, the infectivity of feces-derived human HEV is higher than that of EDTA-plasma-derived HEV both in vitro and in vivo. Persistent HEV gt3 infections in chimeric mice show preferential viral shedding toward mouse bile and feces, paralleling the course of infection in humans.