Role of EBV Lytic Infection in Viral Tumorigenesis

EBV 裂解性感染在病毒肿瘤发生中的作用

• 批准号: 9891040
• 负责人: Shannon Celeste Kenney
• 金额: $ 50.75万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9891040
• 关键词: AIDS-Related Lymphoma; Acyclovir; Africa; African; Antiviral Agents; Automobile Driving; B-Lymphocytes; BZLF1 gene; Binding; Biological Markers; Cells; Child; DNA biosynthesis; DNA-Directed DNA Polymerase; Development; Early Promoters; Epithelial Cells; Epstein-Barr Virus Infections; Epstein-Barr Virus latency; FDA approved; Frequencies; Gene Expression; Growth; Growth Factor; Horizontal Disease Transmission; Human; Human Herpesvirus 4; Immediate-Early Genes; Immunocompetent; Immunosuppression; Impairment; In Vitro; Individual; LMP1; Laboratories; Lymphoma; Lymphomagenesis; Lytic; Lytic Phase; Malaria; Malignant Neoplasms; Modeling; Mutation; Nasopharynx Carcinoma; Non-Malignant; Nuclear Pore Complex; Patients; Pharmaceutical Preparations; Phenotype; Plasma; Polymerase Gene; Proteins; Risk; Role; Tissues; Umbilical Cord Blood; Variant; Viral; Viral Genes; Viral Load result; Viral Proteins; Viral load measurement; Virus Diseases; Virus Replication; Xenograft Model; co-infection; humanized mouse; in vivo; infected B cell; lytic gene expression; lytic replication; malaria infection; mouse model; mutant; neoplastic cell; predictive marker; prevent; promoter; prototype; release factor; transcription factor; tumor; tumorigenesis; vaccination strategy; viral DNA; viral transmission

PROJECT SUMMARY / ABSTRACT Epstein-Barr virus (EBV) is an important cause of human cancers world-wide, including both B cell and epithelial cell malignancies. Although the role of EBV-encoded latency proteins in driving these cancers is well accepted, the importance of lytic viral proteins remains relatively controversial. Nevertheless, lytic infection in a subset of EBV-infected cells in vivo may be required for efficient EBV-induced lymphoma formation. We previously showed that a lytic-defective EBV mutant (missing the BZLF1 (Z) immediate-early (IE) gene) is impaired for the ability to form lymphomas in a humanized mouse model that allows horizontal virus transmission. In addition, we and others have identified growth factors and immunosuppressive factors released from lytically infected B cells that likely enhance the growth and survival of nearby latently infected B cells. Furthermore, we have recently discovered that a BZLF1 promoter variant (known as Zp-V3) that is over-represented in certain EBV-positive malignancies (including NPC and AIDS-related lymphomas) relative to its frequency in non-malignant tissues confers enhanced lytic viral reactivation in vitro due to binding of the cellular NFAT transcription factor to the Zp-V3 variant (but not the prototype promoter, Zp-P). Although the Zp-V3 form of the promoter is relatively uncommon in type 1 EBV strains, it is present in all type 2 strains (which are very common in the malaria belt of Africa). These results suggest that enhanced lytic EBV infection increases the likelihood of EBV-induced lymphomas in vivo, and that a particular cancer-associated variant of the Z promoter promotes lytic infection in EBV-infected B cells. In this proposal, we will use two different humanized mouse models to compare the phenotypes of EBV containing the Zp-P form versus the cancer- associated (Zp-V3) form of the BZLF1 promoter, and to explore mechanism(s) by which lytic EBV infection promotes lymphomagenesis. We will also determine whether EBV loads are higher in malaria-infected children co-infected with Zp-V3 containing EBV strains versus Zp-P containing strains. Our Specific Aims are 1) to use humanized mouse models to examine the in vivo phenotypes of Zp-V3 versus Zp-P containing type 1 or type 2 EBV strains; 2) to compare the phenotypes of BALF5 (the viral DNA polymerase)-deleted versus BZLF1-deleted EBV mutants in humanized mice, and explore whether blocking lytic EBV DNA replication with the antiviral drug, acyclovir, inhibits the development of EBV-induced lymphomas; and 3) to determine whether the Zp-V3 promoter variant is associated with higher plasma levels of EBV in malaria-infected African children. We hypothesize that the EBV Zp-V3 variant will enhance EBV-induced lymphomas in humanized mice by increasing lytic EBV infection, and that this variant is also associated with enhanced lytic EBV replication in malaria-infected children. If so, these results will suggest that the presence of the Zp-V3 variant may be a useful biomarker for predicting increased risk of EBV-induced malignancy in humans.

项目概要/摘要 Epstein-Barr 病毒 (EBV) 是全世界人类癌症的重要原因，包括 B 细胞和 上皮细胞恶性肿瘤。尽管 EBV 编码的潜伏蛋白在驱动这些癌症中的作用尚不清楚 尽管已被广泛接受，但裂解病毒蛋白的重要性仍然存在相对争议。尽管如此，溶解 有效的 EBV 诱导淋巴瘤可能需要体内感染 EBV 感染细胞的子集 形成。我们之前表明，裂解缺陷型 EBV 突变体（缺失 BZLF1 (Z) 立即早期 （IE）基因）在人源化小鼠模型中形成淋巴瘤的能力受损，该模型允许水平 病毒传播。此外，我们和其他人还发现了生长因子和免疫抑制因子 从裂解性感染的 B 细胞中释放出来，可能会增强附近潜伏感染的 B 细胞的生长和存活 B细胞。此外，我们最近发现了 BZLF1 启动子变体（称为 Zp-V3） 在某些 EBV 阳性恶性肿瘤（包括鼻咽癌和艾滋病相关淋巴瘤）中比例过高 由于其在非恶性组织中的出现频率，由于与 Zp-V3 变体的细胞 NFAT 转录因子（但不是原型启动子 Zp-P）。虽然 Zp-V3 形式的启动子在 1 型 EBV 毒株中相对罕见，但存在于所有 2 型毒株中 （这在非洲疟疾带非常常见）。这些结果表明增强的裂解性 EBV 感染 增加了 EBV 体内诱发淋巴瘤的可能性，并且特定的癌症相关变异 Z 启动子的启动子促进 EBV 感染的 B 细胞的裂解感染。在本提案中，我们将使用两种不同的 人源化小鼠模型来比较包含 Zp-P 形式的 EBV 与癌症的表型 BZLF1启动子的相关（Zp-V3）形式，并探索裂解性EBV感染的机制 促进淋巴瘤发生。我们还将确定感染疟疾的人中 EBV 载量是否较高 儿童同时感染含有 Zp-V3 的 EBV 菌株与含有 Zp-P 的菌株。我们的具体目标是 1) 使用人源化小鼠模型来检查 Zp-V3 与 Zp-P 含有型的体内表型 1型或2型EBV毒株； 2) 比较 BALF5（病毒 DNA 聚合酶）删除与删除的表型 人源化小鼠中 BZLF1 缺失的 EBV 突变体，并探讨是否用 抗病毒药物阿昔洛韦可抑制 EB 病毒诱导的淋巴瘤的发展； 3) 确定 Zp-V3 启动子变异是否与感染疟疾的非洲人血浆中较高的 EBV 水平相关 孩子们。我们假设 EBV Zp-V3 变体将增强人源化中 EBV 诱导的淋巴瘤 小鼠通过增加裂解性 EBV 感染，并且该变体也与增强的裂解性 EBV 相关 在感染疟疾的儿童中复制。如果是这样，这些结果将表明 Zp-V3 变体的存在 可能是预测人类 EB 病毒诱发恶性肿瘤风险增加的有用生物标志物。