Cell binding tropism of rat hepatitis E virus is a pivotal determinant of its zoonotic transmission to humans.

Abstract

Classically, all hepatitis E virus (HEV) variants causing human infection belong to the genus <i>Paslahepevirus</i> (HEV-A). However, the increasing cases of rat HEV infection in humans since 2018 challenged this dogma, posing increasing health threats. Herein, we investigated the underlying mechanisms dictating the zoonotic potentials of different HEV species and their possible cross-protection relationships. We found that rat HEV virus-like particles (HEV^VLPs) bound to human liver and intestinal cells/tissues with high efficiency. Moreover, rat HEV^VLPs and infectious rat HEV particles penetrated the cell membrane and entered human target cells postbinding. In contrast, ferret HEV^VLPs showed marginal cell binding and entry ability, bat HEV^VLPs and avian HEV^VLPs exhibited no binding and entry potency. Structure-based three-dimensional mapping identified that the surface spike domain of rat HEV is crucial for cell binding. Antigenic cartography indicated that rat HEV exhibited partial cross-reaction with HEV-A. Intriguingly, sera of HEV-A infected patients or human HEV vaccine Hecolin® immunized individuals provided partial cross-protection against the binding of rat HEV^VLPs to human target cells. In summary, the interactions between the viral capsid and cellular receptor(s) regulate the distinct zoonotic potentials of different HEV species. The systematic characterization of antigenic cartography and serological cross-reactivity of different HEV species provide valuable insights for the development of species-specific diagnosis and protective vaccines against zoonotic HEV infection.