Orthropoxvirus Pathogenesis and Vaccines

描述（由申请方提供）：正痘病毒（OPV）是一种大型DNA病毒，对其天然宿主具有高度致死性。天花由人类特异性OPV天花病毒（VARV）产生，并通过接种活牛痘病毒（VACV）（一种轻度致病性OPV）根除。尽管取得了这一成功，但我们仍然对OPV在其天然宿主中的高致病性的原因以及天花疫苗的保护机制知之甚少。研究OPV对人类健康很重要，原因有几个：1）OPV在许多动物物种中很常见，其中一些病毒可能跨越物种障碍，成为人类病原体。2)人们担心，VARV可能被用作武器。3)根据目前的标准，基于活VACV的疫苗是不安全的，并且灭活VACV不能保护。4)由于天花疫苗是如此有效，了解它如何保护可能是有价值的，以开发疫苗，以其他病毒，包括其他大型DNA病毒，如疱疹病毒。在这个项目中，我们的模型将是小鼠OPV肢脱病病毒（ECTV），在易感小鼠品系中产生鼠痘。OPV的一个显著特征是它们表达分泌的免疫应答调节剂（IRM）。在具体目标1中，我们将构建和表征不表达特异性IRMs的ECTV突变体。将对这些突变体进行检测，并与野生型病毒进行比较，以确定其在组织培养物中的生长情况;其在免疫缺陷和免疫活性小鼠中传播和诱导病理的能力;以及其诱导的体液和细胞免疫应答的强度和类型。任何发现都应适用于这些IRM的直系同源物在其他致命OPV感染（如人类天花）中的功能。在特定目标2中，我们将确定暴露于病毒体表面的特定IRMs和结构蛋白是否是保护性免疫反应的天然靶点，以及它们是否可以用作疫苗。这些实验很重要，因为它们将剖析感染诱导的保护性免疫机制，并测试非感染性抗OPV疫苗的新方法。

DESCRIPTION (provided by applicant): Orthopoxviruses (OPVs) are large DNA viruses that can be highly lethal to their natural hosts. Smallpox was produced by the human-specific OPV variola virus (VARV) and was eradicated through vaccination with live vaccinia virus (VACV), a mildly pathogenic OPV. Despite this success, we still know little about the reasons for the high pathogenicity of OPVs in their natural hosts and the mechanisms whereby the smallpox vaccine protects. Studying OPVs is important for human health for several reasons: 1) OPVs are common in many animal species and some of these viruses could jump the species barrier and become human pathogens. 2) There is fear that VARV could be used as a weapon. 3) The vaccine based on live VACV is not safe by current standards and killed VACV does not protect. 4) Since the smallpox vaccine is so effective, understanding how it protects may be valuable to develop vaccines to other viruses, including other large DNA viruses such as herpesviruses. In this project our model will be the mouse OPV ectromelia virus (ECTV) that produces mousepox in susceptible strains of mice. A notable feature of OPVs is their expression of secreted immune response modifiers (IRMs). In Specific Aim 1 we will construct and characterize ECTV mutants that do not express specific IRMs. These mutants will be tested and compared with wild type virus for their growth in tissue culture; their ability to spread and induce pathology in immunodeficient and immunocompetent mice; and the strength and type of humoral and cellular immune response that they induce. Any findings should be applicable to the function of the orthologs of those IRMs in other lethal OPV infections such as smallpox in humans. In Specific Aim 2, we will determine whether specific IRMs and structural proteins exposed to the surface of virions are natural targets of protective immune responses and whether they can be used as vaccines. These experiments are important because they will dissect the mechanisms of protective immunity induced by infection and test a novel approach to non-infectious anti-OPV vaccines.