In vivo Interactions Between a Gamma-Herpesvirus and Innate Immune Responses

通过逃避宿主的免疫监视，疱疹病毒可以在宿主体内持续存在并引起各种疾病。因此，了解病毒免疫逃逸的机制不仅是开发疫苗的方法来控制疱疹病毒疾病是必不可少的，而且可能导致新的发现宿主先天防御系统。在宿主免疫系统的两翼--先天性免疫和适应性免疫中，先天性免疫应答是抑制疱疹病毒粘膜感染的关键，因为它们是深刻影响疱疹病毒免疫控制的第一道防线。γ-疱疹病毒亚科的成员在它们在淋巴细胞中建立潜伏感染并在感染的宿主中引起良性或恶性肿瘤的能力方面是不同的。卡波西肉瘤相关疱疹病毒（KSHV/HHV-8）是两种人类疱疹病毒之一， 与肿瘤有关，如卡波西肉瘤和原发性积液 淋巴瘤尽管病毒的医学重要性，人类γ-疱疹病毒感染的研究主要限于体外实验，因为它们的宿主范围有限。因此，小鼠感染鼠γ疱疹病毒68（MHV-68），这是生物学和遗传学相关的， KSHV-HHV-8已被用作探索γ-疱疹病毒感染期间宿主-病毒相互作用的小动物模型。 对MHV-68 ORF表达文库进行了筛选，发现MHV-68中有3个非必需基因是保守的 在γ-疱疹病毒中，阻断I型干扰素（IFN）诱导的信号传导。有趣的是，所有三个ORF共享一个保守的dUTPase-related domain（DURO），尽管其中只有一个具有酶活性。我们建议这三个病毒dUTPase-related蛋白（DURPs）的特点和它们的抗干扰素功能的生物学意义。此外，灭活病毒抗IFN基因以产生减毒活病毒的策略被探索作为疫苗接种的新策略。这项研究将评估一组保守病毒蛋白的功能，证明疫苗方法的可行性，并为未来的临床应用奠定基础。 采用类似的方法，本项目4将使用MHV-68感染小鼠作为模型系统来评估 其他病毒免疫逃避基因的生物学相关性和病毒-宿主相互作用已在项目1，2和3中确定，并评估其在疫苗开发中的潜在效用。

By evading host immune surveillance, herpesviruses can persist in hosts and cause various diseases. Thus, understanding the mechanisms of viral immune evasion is not only essential for developing vaccine approaches to control herpesviral diseases, but also may lead to novel discoveries about the host innate defense system. Of the two wings of the host immune system, innate and adaptive, innate immune responses are very critical for restraining mucosal infection of herpesvirus because they are the first line of defense that profoundly affects the immune control of herpesvirus. Members of the gamma-herpesvirus subfamily are distinct in their ability to establish latent infections in lymphocytes and cause benign or malignant tumors in infected hosts. Kaposi's sarcoma-associated herpesvirus (KSHV/HHV-8) is one of two human gamma-herpesviruses and is associated with tumors, such as Kaposi's sarcoma and primary effusion lymphoma. In spite of the viruses' medical importance, the studies of human gamma-herpesvirus infection have been limited mostly to in vitro experiments because of their restricted host range. Therefore, mouse infection by murine gammaherpesvirus68 (MHV-68), which is biologically and genetically related to KSHV-HHV-8, has been used as a small animal model for exploring host-virus interactions during gamma-herpesvirus infection. A MHV-68 ORF expression library was screened, which reveal that three non-essential genes conserved among gamma-herpesviruses, block signaling induced by type I interferons (IFN). Interestingly, all three ORFs share a conserved dUTPase-related domain (DURO), although only one of them possesses enzymatic activity. We propose to characterize these three viral dUTPase-related proteins (DURPs) and the biological significance of their anti-IFN functions. Furthermore, a strategy of inactivating viral anti-IFN genes to generate a live-attenuated virus was explored as a new strategy for vaccination. The proposed research will assess the function of a group of conserved viral proteins, demonstrate the feasibility of the vaccine approach and establish a foundation for future clinical application. Taking a similar approach, this Project 4 will use MHV-68 infection of mice as a model system to assess the biological relevance of the other viral immune evasion genes and virus-host interactions that have been identified in Project 1, 2 and 3, and evaluate their potential utilities in vaccine development.