Fu Rebecca, Jordan Paula, Engels Zoe, Weihs Jasmin Alara, Mürle Josias, Chi Huanting, Burbano de Lara Sebastian, Helm Barbara, Klöhn Mara, Hu Jungen, Freistaedter Andrew, Boettler Tobias, Binder Marco, Klingmüller Ursula, Steinmann Eike, Lozach Pierre-Yves, Tubiana Thibault, Lemon Stanley M, Dao Thi Viet Loan
Schaller Research Group, Department of Infectious Diseases, Virology, Heidelberg University, Medical Faculty Heidelberg, Heidelberg, Germany.
German Centre for Infection Research (DZIF), Partner Site Heidelberg, Heidelberg, Germany.
Nat Commun. 2025 Jun 26;16(1):5403. doi: 10.1038/s41467-025-61071-y.
Hepatitis E virus (HEV) is a major cause of acute hepatitis and mainly transmitted faecal-orally. HEV particles present in faeces are naked (nHEV), whereas those found in the blood are quasi-enveloped (eHEV) with a cell-derived lipid membrane. Despite its global health impact, the cellular life cycle of HEV remains poorly understood, particularly regarding the mechanisms of viral entry into host cells. To address this knowledge gap, we develop a high content RNA-FISH-based imaging assay that allows for the investigation of the entry pathways of both naked and quasi-enveloped HEV particles. Surprisingly, we find that integrin α3, previously implicated in nHEV cell entry, is not expressed in the cell types that are most permissive for HEV infection. Instead, we identify integrin β1 (ITGB1) pairing with different α-integrins as the key player mediating nHEV cell entry. Our results indicate that the interaction of nHEV with ITGB1 facilitates entry through Rab11-positive recycling endosomes. In contrast, eHEV particles do not interact with ITGB1 and enter cells using a classical endocytic route via Rab5a-positive early endosomes. The entry of both types of HEV particles requires endosomal acidification and proteolytic cleavage by lysosomal cathepsins, which ultimately results in delivery of the HEV genome to the cytoplasm.
戊型肝炎病毒（HEV）是急性肝炎的主要病因，主要通过粪口途径传播。粪便中存在的HEV颗粒是无包膜的（nHEV），而血液中发现的HEV颗粒是具有细胞衍生脂质膜的准包膜型（eHEV）。尽管HEV对全球健康有影响，但其细胞生命周期仍知之甚少，尤其是病毒进入宿主细胞的机制。为了填补这一知识空白，我们开发了一种基于高内涵RNA-FISH的成像检测方法，用于研究无包膜和准包膜HEV颗粒的进入途径。令人惊讶的是，我们发现先前与nHEV细胞进入有关的整合素α3在对HEV感染最敏感的细胞类型中不表达。相反，我们确定与不同α整合素配对的整合素β1（ITGB1）是介导nHEV细胞进入的关键因素。我们的结果表明，nHEV与ITGB1的相互作用促进了通过Rab11阳性循环内体的进入。相比之下，eHEV颗粒不与ITGB1相互作用，而是通过Rab5a阳性早期内体利用经典的内吞途径进入细胞。两种类型的HEV颗粒的进入都需要内体酸化和溶酶体组织蛋白酶的蛋白水解切割，最终导致HEV基因组传递到细胞质中。
