[Research progress in the etiology of hepatitis type E virus]

Abstract

Hepatitis type E virus (HEV) is a significant infectious zoonotic disease that causes hepatitis E. The disease is primarily transmitted via the fecal-oral route through contaminated water or food and is transmissible between species and genera. The causative agent for the disease is the hepatitis type E virus, which is a member of the Hepadnaviridae family and a single-stranded RNA virus. Its 7.2 kb genome mainly contains three open reading frames (ORFs): ORF1 encodes a non-structural polyprotein that mediates viral replication and transcription; ORF2 encodes a capsid protein and free antigen that induce neutralizing antibodies; ORF3 partially overlaps with ORF2 and encodes a small multifunctional protein involved in virion formation and release. HEV has a unique dual life cycle: it is excreted into feces in the form of naked virions but circulates in the blood in the form of "quasi-enveloped" particles. The two kinds of virus particles adsorb and penetrate the host cell in distinct ways, then internalize and decapsulate to replicate the genome, thereby producing more virion and releasing it outside the cell to mediate the virus's spread. This paper reviews the morphological characteristics, genome structure, encoded proteins, and function of HEV virus-like particles in order to provide a theoretical basis for basic research and comprehensive disease prevention and control.

Keywords: Genome structure; Hepatitis E virus; Protein function; Virion morphology.

图1. 戊型肝炎病毒和“准囊膜”戊型肝炎病毒体外传播途径

图2. 戊型肝炎病毒基因组结构

图3. 外泌体和准囊膜戊型肝炎病毒粒子电镜图^[26]

注：HEV：戊型肝炎病毒；A：从未感染的细胞；B：HEV感染的PLC/PRF/5细胞培养上清液中纯化的外泌体的透射电镜图像，负染，100nm；C：从HEV感染细胞的培养上清液中纯化的外泌体中发现的病毒样颗粒的高倍放大图像，50nm