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，并导致各种疾病。因此，了解病毒免疫逃避的机制不仅对于开发控制疱疹病毒疾病的疫苗方法至关重要，而且还可能导致关于宿主固有防御系统的新发现。在宿主免疫系统的先天和获得性两只翅膀中，先天免疫反应对于抑制疱疹病毒的黏膜感染非常关键，因为它们是深刻影响疱疹病毒免疫控制的第一道防线。伽玛疱疹病毒亚家族的成员在建立淋巴细胞潜伏感染和在受感染宿主中引起良性肿瘤或恶性肿瘤方面具有独特的能力。卡波西肉瘤相关疱疹病毒(KSHV/HHV-8)是人类 与肿瘤有关，如卡波西氏肉瘤和原发积液 淋巴瘤。尽管这些病毒具有重要的医学价值，但由于其宿主范围的限制，对人类伽马疱疹病毒感染的研究大多局限于体外实验。因此，小鼠感染小鼠伽马疱疹病毒68(MHV-68)，这与生物学和遗传学有关 KSHV-HHV-8已被用作探索伽玛-疱疹病毒感染过程中宿主与病毒相互作用的小动物模型。 对MHV-68ORF文库进行了筛选，发现有3个非必需基因保守 在伽马疱疹病毒中，阻断I型干扰素(IFN)诱导的信号转导。有趣的是，这三个ORF都有一个保守的dUTPase相关结构域(Duro)，尽管它们中只有一个具有酶活性。我们拟对这三种病毒dUTPase相关蛋白(DURPs)及其抗干扰素功能的生物学意义进行研究。此外，还探索了一种灭活病毒抗干扰素基因以产生减毒活病毒的策略，作为一种新的疫苗接种策略。这项拟议的研究将评估一组保守的病毒蛋白的功能，论证疫苗方法的可行性，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 项目1、2和3中已确定的其他病毒免疫逃避基因和病毒-宿主相互作用的生物学相关性，并评估它们在疫苗开发中的潜在用途。

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.