Mirco Glitscher, Inga Mareike Spannaus, Fabiane Behr, Robin Oliver Murra, Kathrin Woytinek, Daniela Bender, Eberhard Hildt
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Abstract
Background
A peculiar feature of the hepatitis E virus (HEV) is its reliance on the exosomal route for viral release. Genomic replication is mediated via the viral polyprotein pORF1, yet little is known about its subcellular localization.
Methods
Subcellular localization of pORF1 and its subdomains, generated and cloned based on a structural prediciton of the viral replicase, was analyzed via confocal laser scanning microscopy. Exosomes released from cells were isolated via ultracentrifugation and analyzed by isopycnic density gradient centrifugation. This was followed by fluorimetry or Western blot analyses or reverse transcriptase–polymerase chain reaction to analyze separated particles in more detail.
Results
We found pORF1 to be accumulating within the endosomal system, most dominantly to multivesicular bodies (MVBs). Expression of the polyprotein’s 7 subdomains revealed that the papain-like cysteine-protease (PCP) is the only domain localizing like the full-length protein. A PCP-deficient pORF1 mutant lost its association to MVBs. Strikingly, both pORF1 and PCP can be released via exosomes. Similarly, genomic RNA still is released via exosomes in the absence of pORF2/3.
Conclusions
Taken together, we found that pORF1 localizes to MVBs in a PCP-dependent manner, which is followed by exosomal release. This reveals new aspects of HEV life cycle, because replication and release could be coupled at the endosomal interface. In addition, this may mediate capsid-independent spread or may facilitate the spread of viral infection, because genomes entering the cell during de novo infection readily encounter exosomally transferred pORF1.
期刊介绍：
"Cell and Molecular Gastroenterology and Hepatology (CMGH)" is a journal dedicated to advancing the understanding of digestive biology through impactful research that spans the spectrum of normal gastrointestinal, hepatic, and pancreatic functions, as well as their pathologies. The journal's mission is to publish high-quality, hypothesis-driven studies that offer mechanistic novelty and are methodologically robust, covering a wide range of themes in gastroenterology, hepatology, and pancreatology.
CMGH reports on the latest scientific advances in cell biology, immunology, physiology, microbiology, genetics, and neurobiology related to gastrointestinal, hepatobiliary, and pancreatic health and disease. The research published in CMGH is designed to address significant questions in the field, utilizing a variety of experimental approaches, including in vitro models, patient-derived tissues or cells, and animal models. This multifaceted approach enables the journal to contribute to both fundamental discoveries and their translation into clinical applications, ultimately aiming to improve patient care and treatment outcomes in digestive health.
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