Entry and replication of positive-sense, RNA viruses

正义 RNA 病毒的进入和复制

• 批准号: 10272224
• 负责人: Joseph Marcotrigiano
• 金额: $ 108.88万
• 依托单位: NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10272224
• 关键词: Affect; Antibody Response; Antiviral Therapy; Apolipoproteins; Binding; Biochemical; Biophysics; CD81 gene; Cells; Centers for Disease Control and Prevention (U.S.); Chronic Hepatitis C; Complementarity Determining Regions; Complex; Development; Epitopes; Exposure to; Foundations; Genotype; Glycoproteins; Goals; Hepatitis C; Hepatitis C Vaccine; Hepatitis C virus; Immune Evasion; Immune system; Individual; Infection; Infection prevention; International; Membrane Fusion; Membrane Glycoproteins; Molecular Conformation; Mutation; Patients; Peptides; Pharmacotherapy; Polyvalent Vaccine; Process; Production; Proteins; Public Health; Publishing; RNA Viruses; Recombinants; Research; Research Personnel; Resources; Rest; Risk Behaviors; Role; Route; SR-BI receptor; Site; Structure; Surface; Vaccines; Viral; Virion; Virus; biophysical techniques; cost; density; glycosylation; intravenous drug use; neutralizing antibody; novel; particle; receptor

HCV represents a major global public health problem, infecting approximately 70 million people worldwide. There is currently no approved vaccine to counter HCV infection, and it is estimated that there are more than 40,000 new infections annually in the US alone with an additional 3-4 million new infections per year in the rest of world (Center for Disease Control). Chronic HCV infection is curable by an effective, albeit expensive, antiviral therapy ($50,000/treated patient). Drug treatment is not, however, a feasible route to worldwide eradication of HCV infection, as the cost of doing so would be prohibitive. Moreover, successful treatment of a patient infected with one viral genotype does not preclude re-infection with another. The drug treatment approach is also complicated by the fact that most affected individuals are unaware that they are infected, and many engage in risky behaviors, such as intravenous drug use. Simply put, the best long term solution is to invest considerable intellectual and financial resources in discovery and development of a polyvalent vaccine effective against most, if not all, HCV viral genotypes. The HCV virion is a structurally heterogeneous particle which harbors a buoyant density lower than that of most other viruses, making it unique among known viruses. The virion associates with several host derived apolipoproteins and two surface glycoproteins, E1 and E2. E2 are responsible for cell targeting by interacting with the cellular receptors CD81 and scavenger receptor class B, type I (SR-BI). The function of E1 remains poorly understood. We and others published that the E2 core structure has a novel domain organization, lacks the hallmarks of a typical fusion peptide, and does not undergo large conformational or oligomeric changes upon exposure to low pH. As a result, E2 does not appear to have a direct role in membrane fusion, implying that E1 alone or the E1E2 heterodimer is responsible for the fusion process. These comprehensive structural, biochemical, and biophysical results have established a foundation to better define the functional roles of the envelope glycoproteins in HCV infection. Conserved viral epitopes on the surface of HCV can be made considerably more accessible to the immune system by deletion or modifying the immune evasion mechanism present on the virus. Working with an international group of investigators we deleted the hypervariable region 1 and selected glycosylation sites on the surface of E2, which have been shown to interfere with binding of several neutralizing antibodies (Khera et al. J Hepatol 2019). Interestingly, recombinant E2 proteins carrying these mutations are unable to elicit cross-neutralizing antibodies, suggesting that exposure of conserved epitopes is not sufficient to focus antibody responses on production of cross-neutralizing antibodies. The results of this study highlights deficiencies in our understanding of HCV entry and neutralization, providing the impetus for continued research on HCV entry.

丙型肝炎病毒是一个重大的全球公共卫生问题，全世界约有7000万人感染。目前还没有被批准的疫苗来对抗丙型肝炎病毒感染，据估计，仅在美国每年就有超过4万新感染病例，世界其他地区每年新增感染病例300-400万(疾病控制中心)。慢性丙型肝炎病毒感染可以通过一种有效的、尽管昂贵的抗病毒疗法来治愈(每名接受治疗的患者收费5万美元)。然而，药物治疗并不是在世界范围内根除丙型肝炎病毒感染的可行途径，因为这样做的成本将令人望而却步。此外，成功治疗感染了一种病毒的患者并不排除再次感染另一种病毒。药物治疗方法也因以下事实而变得复杂：大多数受影响的人没有意识到自己被感染了，许多人从事危险行为，如静脉吸毒。简而言之，最好的长期解决方案是投入大量的智力和财政资源，发现和开发一种对大多数(如果不是全部)丙型肝炎病毒基因有效的多价疫苗。 丙型肝炎病毒粒子是一种结构不同的粒子，其浮力密度低于大多数其他病毒，使其在已知病毒中独一无二。病毒粒子与几种宿主来源的载脂蛋白和两种表面糖蛋白E1和E2结合。E2通过与细胞受体CD81和清道夫受体B类，I型(SR-BI)相互作用而起到细胞靶向作用。对于E1的功能目前仍知之甚少。我们和其他人发表了E2核心结构具有新的结构域组织，缺乏典型融合肽的特征，并且在低pH值下不会发生大的构象或寡聚体变化。因此，E2似乎在膜融合中没有直接作用，这意味着E1单独或E1E2异源二聚体负责融合过程。这些综合的结构、生化和生物物理结果为更好地确定包膜糖蛋白在丙型肝炎病毒感染中的功能作用奠定了基础。 通过删除或修改病毒表面存在的免疫逃避机制，可以使免疫系统更容易获得丙型肝炎病毒表面保守的病毒表位。与一个国际研究小组合作，我们删除了E2表面的高变区1和选定的糖基化位点，这已被证明干扰了几种中和抗体的结合(Khera等人)。J Hepatol 2019)。有趣的是，携带这些突变的重组E2蛋白不能诱导交叉中和抗体，这表明暴露保守的表位不足以将抗体反应集中在产生交叉中和抗体上。这项研究的结果突出了我们在了解丙型肝炎病毒进入和中和方面的不足，为继续研究丙型肝炎病毒进入提供了动力。