ACTIVATION OF KAPOSI SARCOMA ASSOCIATED HERPES VIRUS

描述（改编自申请人的摘要）：γ疱疹病毒 卡波西肉瘤相关疱疹病毒（Kaposi's sarcoma-associated herpesvirus，KSHV） 疱疹病毒8（HHV 8）是两种恶性肿瘤的可能病原体， 卡波西肉瘤（KS）和原发性渗出性淋巴瘤（PEL），发生在 艾滋病患者。在这两种KSHV相关的大多数细胞中， 病毒在肿瘤中保持潜伏状态，但在细胞亚群中 KSHV被激活进入裂解周期基因表达。申请人已经发现 许多KSHV基因是细胞趋化因子的同源物， 细胞因子和抗凋亡因子可能在病毒感染中起关键作用， 生物学在病毒基因表达的裂解期表达， KS活组织检查和衍生自PEL的细胞系。作为一个开创性的线索， 裂解周期激活的机制，我们已经确定了KSHV立即早期 一种名为KSHV/Rta的基因产物，部分编码于ORF 50中， PEL细胞中包括vIL 6的裂解周期基因的表达。其全球 目的是了解ORF 50基因产物在开关中的作用， 在B细胞和人淋巴细胞中， 微血管内皮细胞调查人员将分析这些事件 在KSHV/Rta表达的下游，以确定ORF 50/Rta是否有能力 来激活整个病毒裂解循环程序使用核酶抑制， 申请人将了解ORF 50是否是病毒重新激活所必需的。 他们将研究KSHV/Rta的作用机制， 直接，通过结合下游基因启动子中的DNA，或间接 通过其他蛋白质识别DNA。他们将探索它是否会自动刺激 自己的表达。他们将描绘出导致激活 ORF 50表达，最终了解这种激活是否伴随着 与ORF 50启动子结合的细胞蛋白的获得或丧失 基因他们将确定KSHV/ORF 50产品是否起激活作用， 在造血和内皮细胞的从头感染中的作用或仅 在裂解循环再激活期间起作用。拟议的实验采用了 生物学、分子学、遗传学和生物化学方法相结合， KSHV生命周期的核心特征。这些研究应该提供一些见解， KSHV相关疾病的分子发病机制，并解决基本的 关于控制致癌疱疹病毒基因表达的问题。

DESCRIPTION (Adapted from the Applicant's Abstract): The gammaherpesvirus variably known as Kaposi's sarcoma-associated herpesvirus (KSHV) or human herpesvirus eight (HHV8) is the likely etiologic agent of two malignancies, Kaposi's sarcoma (KS) and primary effusion lymphoma (PEL), that occur in patients with AIDS. In the majority of cells of these two KSHV-associated tumors the virus remains in a latent state, but in a subpopulation of cells KSHV is activated into lytic cycle gene expression. The applicants have found that a number of KSHV genes that are homologues of cellular chemokines, cytokines and anti-apoptotic factors that likely play critical roles in virus biology are expressed during the lytic phase of viral gene expression both in KS biopsies and in cell lines derived from PEL. As a seminal clue to the mechanism of lytic cycle activation we have identified a KSHV immediate-early gene product termed KSHV/Rta, partially encoded in ORF50, that activates expression of lytic cycle genes including vIL6 in PEL cells. Their global objective is to understand the role of the ORF50 gene product in the switch between latency and lytic cycle gene expression both in B cells and in microvascular endothelial cells. The investigators will analyze the events downstream of KSHV/Rta expression to determine whether ORF50/Rta is competent to activate the entire viral lytic cycle program. Using ribozyme inhibition the applicants will learn whether ORF50 is essential for reactivation of the virus. They will study the mechanism of action of KSHV/Rta, learning whether it acts directly, by binding DNA in the promoters of downstream genes, or indirectly recognizing DNA via other proteins. They will explore whether it autostimulates its own expression. They will delineate the pathway leading to activation of ORF50 expression, ultimately learning whether this activation is accompanied by acquisition or loss of cellular proteins that bind to the promoter of the ORF50 gene. They will determine whether the KSHV/ORF50 product plays an activating role in de novo infection of hematopoietic and endothelial cells or only functions during lytic cycle reactivation. The proposed experiments employ a combination of biologic, molecular, genetic and biochemical approaches to study a central feature of the KSHV life cycle. The studies should provide insights into molecular pathogenesis of KSHV-associated disease and address fundamental questions about control of oncogenic herpesvirus gene expression.