MOLECULAR BIOLOGY OF TRANSFORMATION BY EPSTEIN-BARR VIRUS

EB病毒(EBV)核蛋白2(EBNA-2)是B细胞所必需的 病毒对细胞的转化。这个项目的目标是 探讨EB病毒对B细胞转化的作用机制。 将EBV转化的人淋巴细胞注射到SCID小鼠体内 含有EBV的致命性人类B细胞肿瘤的出现。细胞系 都被开发出含有EBV突变体的病毒，这些突变体除了 他们EBV EBNA-2基因的不同缺失。带有缺失的EB病毒突变体 在EBNA-2的氨基部分含有EBV EBNA-2基因。EB病毒突变体与 EBNA-2的氨基部分缺失降低了转化活性 在体外，在小鼠身上产生肿瘤的速度更慢，而羧基- 末端突变体的转化活性大于或等于 野生型比野生型更快地产生肿瘤。因此， EBNA-2在细胞培养中对淋巴细胞转化都很重要 和B细胞瘤在SCID小鼠体内的生长。 EBV EBNA-2包含一个直接激活转录的结构域；A 14 氨基酸区域具有很大的转录活性，是 对EB病毒的转化至关重要。构建了一种嵌合病毒 它包含部分转录激活结构域，来自 插入的单纯疱疹病毒VP16取代14个氨基酸 EBNA-2中的区域。这种嵌合病毒能够将B细胞 并反式激活EB病毒和B细胞基因的表达。 EBNA-2基因14个氨基酸结构域的单一氨基酸突变 取消转录激活和B细胞转化。因此， EB病毒诱导的B细胞需要转录激活 转型。

Epstein-Barr virus (EBV) nuclear protein 2 (EBNA-2) is essential for B cell transformation by the virus. The goal of this project is to determine the mechanism of B cell transformation by EBV. Injection of EBV-transformed human lymphocytes into SCID mice results in the appearance of fatal human B cell tumors containing EBV. Cell lines were developed that contained EBV mutants that were identical, except for different deletions in their EBV EBNA-2 gene. EBV mutants with deletions in the amino half of EBNA-2 had their EBV EBNA-2 gene. EBV mutants with deletions in the amino half of EBNA-2 had reduced transforming activity in vitro and produced tumors in mice more slowly, while a carboxy- terminal mutant had a transforming activity greater than or equal to wild-type and produced tumors more rapidly than wild-type. Therefore, EBNA-2 is important both for lymphocyte transformation in cell culture and B cell tumor growth in SCID mice. EBV EBNA-2 contains a domain that directly activates transcription; a 14 amino acid region possesses much of the transcriptional activity and is essential for transformation by EBV. A chimeric virus was constructed that contained a portion of the transcriptional activation domain from the herpes simplex virus VP16 inserted in place of the 14 amino acid region in EBNA-2. This chimeric virus was able to transform B lymphocytes and transactivate expression of EBV and B cell genes. Mutation of a single amino acid in the 14 amino acid domain of EBNA-2 abolished transcriptional activation and B cell transformation. Thus, transcriptional activation is required for EBV-induced B cell transformation.