Role of KSHV ORF45 in Viral Immune Evasion & Replication

KSHV ORF45 在病毒免疫逃避中的作用

• 批准号: 7007688
• 负责人: FANXIU ZHU
• 金额: $ 17.77万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-01-15 至 2006-08-04
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7007688
• 关键词: SDS polyacrylamide gel electrophoresis; X ray; biological signal transduction; flow cytometry; host organism interaction; human herpesvirus 8; human tissue; immediate early protein; immunoprecipitation; interferon inducers; interferons; latent virus infection; microorganism immunology; pathologic process; phosphorylation; polymerase chain reaction; protein protein interaction; protein structure function; small interfering RNA; transfection; tumor suppressor proteins; virus infection mechanism; virus load; virus replication

DESCRIPTION (provided by applicant): This proposal is response to RFA-DE-05-001. Kaposi's sarcoma associated herpesvirus (KSHV) is etiologically linked to Kaposi's sarcoma (KS), the most common malignancy and oral cancer in AIDS patients. Unlike other DNA tumor viruses, KSHV lytic life cycle contributes significantly to the formation of KS lesions by facilitating viral spread to the target sites and releasing paracrine factors to support the growth of KS tumor cells. Recent study found that KSHV episomes in latently infected cells were rapidly lost due to cell proliferation, reactivation and infection processes constantly happen in KS lesion in order to maintain viral infected cell population. Reactivation and infection normally inevitably triggers host innate antiviral response including interferon (IFN) signaling pathway. However, KSHV evolved elaborate mechanism to evade IFN signaling which enable its recurring reactivation and infection process undetected by host immune surveillance system. We have found KSHV immediate early protein ORF45 interacts with cellular interferon regulatory factor-7 (IRF-7) and prohibits IRF-7 from being transported to the nucleus. As a result, ORF45 efficiently inhibits the induction of type I interferon during viral infection. In addition, ORF45 protein is also found in KSHV virion as tegument protein. The immediate-early expression kinetics as well as the presence of ORF45 in virion suggests critical roles of ORF45 in antagonizing host antiviral defenses and viral propagation. We hypothesize that KSHV uses ORF45 protein to ensure a protection from host immune responses and a successful viral infection and reactivation. In this proposal, first, we will investigate the mechanism that ORF45 use to block the IRF-7 activation and interferon induction. Second, we will examine the role of ORF45 in antagonizing host antiviral response with both gain-of-function and loss-of-function approach. Third, we will assess the impact of ORF45 on KSHV reactivation and pathogenicity by disrupting ORF45 gene function With SiRNA or recombinant ORF45 deficient KSHV. The proposed study will reveal the mechanism that viruses use to defeat host immune defenses and role of ORF45 in viral infection and pathogenesis. In addition, our research may also suggest novel therapeutic target and strategies in treatment of KSHV-associated malignancies.

描述（由申请人提供）：该建议是对RFA-DE-05-001的响应。 Kaposi的肉瘤相关疱疹病毒（KSHV）与Kaposi的肉瘤（KS）有关，Kaposi的肉瘤（KS）是艾滋病患者中最常见的恶性肿瘤和口腔癌。与其他DNA肿瘤病毒不同，KSHV裂解生命周期通过促进病毒扩散到靶位点并释放旁分泌因子来支持KS肿瘤细胞的生长，从而显着促进KS病变的形成。最近的研究发现，由于细胞的增殖，重新激活和感染过程，KS病变中不断发生的潜在感染细胞中的KSHV偶发迅速丢失，以维持病毒感染的细胞群体。重新激活和感染通常不可避免地会触发包括干扰素（IFN）信号通路在内的先天抗病毒反应。然而，KSHV发展了精致的机制，以逃避IFN信号传导，从而使其重新激活和感染过程未被宿主免疫监视系统发现。我们已经发现KSHV立即蛋白ORF45与细胞干扰素调节因子-7（IRF-7）相互作用，并禁止IRF-7转运到核。结果，ORF45有效抑制了病毒感染期间I型干扰素的诱导。另外，在KSHV病毒素中也发现了ORF45蛋白作为Tegument蛋白。即时表达动力学以及ORF45在Virion中的存在表明ORF45在拮抗宿主抗病毒药防御和病毒传播中的关键作用。我们假设KSHV使用ORF45蛋白来确保免受宿主免疫反应的保护以及成功的病毒感染和重新激活。首先，在此提案中，我们将研究ORF45用于阻止IRF-7激活和干扰素诱导的机制。其次，我们将研究ORF45在拮抗宿主抗病毒反应中的作用，并获得功能障碍和功能丧失方法。第三，我们将通过用siRNA或重组ORF45缺乏KSHV来破坏ORF45基因功能来评估ORF45对KSHV重新激活和致病性的影响。拟议的研究将揭示病毒用来打败宿主免疫防御和ORF45在病毒感染和发病机理中的作用的机制。此外，我们的研究还可能提出了治疗KSHV相关恶性肿瘤的新型治疗靶标和策略。