Mechanism for spread of a quasi-enveloped hepatotropic virus

总结 戊型肝炎病毒（HEV）是一种肠道传播病毒，以裸露的病毒粒子存在于粪便中 或在血液中循环的半包膜病毒体。戊型肝炎病毒的准病毒化有利于非细胞溶解 从受感染的细胞中释放病毒。然而，缺乏病毒包膜蛋白提出了关于机制的问题 戊型肝炎病毒的传播和抗体在自然感染中的作用。HEV每年感染约2000万人， 严重的发病率和死亡率。免疫功能低下的个体持续感染HEV可导致快速 肝纤维化的进展。目前还没有FDA批准的诊断和HEV特异性治疗。我们 长期目标是揭示这种不寻常的病毒在病毒生命周期中的功能作用， 本发明的目的在于确定用于治疗干预的新靶标。本报告的总体目标 项目是了解准病毒在HEV传播中的作用，以及它如何影响抗体介导的 中和已知病毒ORF 3蛋白在HEV的抑制中起关键作用。我们的初步数据 表明ORF 3受到棕榈酰化的调节以介导病毒粒子释放。此外，我们还发现， 中和抗体阻断戊型肝炎病毒在已经感染的细胞中传播的证据。我们 中心假设是ORF 3介导的准抑制是HEV释放到血流中所必需的 并进入胆汁（然后脱落到粪便中），准包膜HEV颗粒介导通过肝脏传播。 新的进入机制，易受抗体进入后中和的影响。我们将检验这一假设 在极化肝细胞培养物和人肝嵌合小鼠中。目的1将定义棕榈酰化的作用 ORF 3的细胞定位和在病毒释放中的功能。目标2将定义蜂窝要求， ORF 3在HEV传播中的作用目标2也将明确抗体在阻断HEV传播中的作用和机制。 所提出的研究的预期成果是对准- 包膜病毒，并可能对其他无包膜病毒，如甲型肝炎，脊髓灰质炎病毒， 肠道病毒在其生命周期的某些阶段也会变成类包膜。这项工作将填补我们的空白 了解准包裹过程及其如何影响病毒传播、发病机制和 免疫力

Summary Hepatitis E virus (HEV), an enterically transmitted virus, exists either as naked virions that are shed in the feces or quasi-enveloped virions that circulate in the blood. The quasi-envelopment of HEV facilitates noncytolytic release of virus from infected cells. However, the lack of viral envelope proteins raises question about mechanism for HEV spread and the role of antibodies in natural infection. HEV infects ~20 million people annually and causes significant morbidity and mortality. Persistent HEV infection in immunocompromised individuals can lead to rapid progression of liver fibrosis. Currently there are no FDA-approved diagnostics and HEV-specific therapies. Our long-term goal is to unravel the functional role(s) of this unusual envelopment in the virus life cycle and pathogenesis for the purpose of identifying novel targets for therapeutic intervention. The overall objective of this project is to understand the role of the quasi-envelopment in HEV spread and how it affects antibody-mediated neutralization. The viral ORF3 protein is known to play a key role in HEV envelopment. Our preliminary data suggest that ORF3 is subjected to regulation by palmitoylation to mediate virion release. In addition, we found evidence that neutralizing antibodies block HEV spread in cells that have already established infection. Our central hypothesis is that ORF3-mediated quasi-envelopment is required for HEV release into the bloodstream and into the bile (then shed into feces), and quasi-enveloped HEV particles mediate spread with the liver via a novel entry mechanism that is susceptible to post-entry neutralization by antibodies. We will test this hypothesis in polarized hepatocyte cell culture and in human liver chimeric mice. Aim 1 will define the role of palmitoylation of ORF3 in its cellular localization and function in virus release. Aim 2 will define the cellular requirements and role of ORF3 in HEV spread. Aim 2 will also define the role and mechanism of antibodies in blocking HEV spread. The expected outcomes of the proposed research are novel insights into the spread mechanism for a quasi- enveloped virus, and may have implications for other non-enveloped viruses such as hepatitis A, poliovirus, and enteroviruses that also become quasi-enveloped at certain stages of their life cycle. This work will fill gaps in our understanding of the quasi-envelopment processes and how it influences virus spread, pathogenesis and immunity.