CLONAL VIRULENCE FEATURES OF THE EBV TERMINAL REGION

在目前的资助期内，我们观察到， 细胞内EB病毒（EBV）基因组的区域表现出 在它们的限制性片段谱中有显著的变化， 直接从三个细胞系中克隆的单个同基因B细胞系， 患者 此外，我们发现，克隆型阵列的 EBV末端区域限制性片段被维持 相对稳定，在体内和体外增殖的EBV- 转化的细胞谱系。 最重要的影响是 下文将对这些调查结果进行探讨。 首先，EBV末端片段分析可用于帮助 确定EBV是否感染肿瘤细胞的祖细胞 或者是否继发感染肿瘤 在最初的扩散和传播之后的人口（ “乘客病毒”概念）。 在这里，我们建议分析EBV 鼻咽肿瘤标本中终末区片段 癌症、非洲伯基特淋巴瘤和艾滋病相关B- 淋巴瘤来回答这个问题。 其次，我们的研究结果表明，克隆的一种机制， 在EBV相关恶性肿瘤中观察到优势。 病毒基因 编码重要的“早期”跨膜蛋白 (IMP/LYDMA）已被其他人本地化到一个站点， 0.6 kb的EBV末端重复序列。 IMP/LYDMA基因 产物被认为在EBV的免疫识别中是重要的， 感染的细胞，以及可能的细胞转化。 我们建议 在细胞内DNA中观察到的克隆异质性 病毒末端区域与顺式作用有关， IMP/LYDMA转录;此处确实提供了证据 表明IMP/LYDMA转录的克隆变异。 我们 建议进一步分析 细胞内EBV末端区。 一、性质和位置 末端区DNA的克隆异质性将进一步 在我们的肿瘤组织细胞克隆中进行了分析。 第二，量化 将获得IMP/LYDMA克隆转录的估计值。 第三，细胞内染色质结构的克隆变异， 将研究EBV末端区域。 最后，一组成员 的等基因细胞克隆将被测试其个体 对自体效应细胞杀伤的敏感性， 细胞毒性试验;这些结果将与 IMP/LYDMA克隆转录的定量估计。 拟议的研究利用目前的发现， EBV-末端区域，这可能是重要的克隆 优势与EBV诱导的肿瘤发生。

In the present funding period, we observed that the terminal regions of intracellular Epstein-Barr virus (EBV) genome exhibit marked variation in their restriction-fragment profile in individual, isogenic B-cell lineages cloned directly from three patients. Furthermore, we found that the clonotypic arrays of EBV terminal-region restriction fragments are maintained relatively stably, during in vivo and in vitro proliferation of EBV- transformed cell lineages. The most important implications of these findings are explored here, as follows. First, EBV terminal-fragment analysis can be used to help determine whether EBV infects the progenitor cell of tumor-cell populations, or whether it secondarily infects the tumor population after initial proliferation and dissemination (the "passenger virus" notion). Here, we propose to analyze the EBV terminal-region fragment in tumor specimens of nasopharyngeal carcinoma, African Burkitt Lymphoma, and AIDS-related B- lymphomas to answer this question. Second, our findings suggest one mechanism of the clonal dominance observed in EBV-related malignancies. The viral gene encoding an important 'early' transmembrane protein (IMP/LYDMA) has been localized by others to a site within about 0.6 kb of the EBV terminal-repeats. The IMP/LYDMA gene product is thought to be important in immune recognition of EBV- infected cells, and possibly in cell transformation. We suggest that the clonal heterogeneity observed in the DNA of intracellular viral terminal regions is associated with cis-acting effects on IMP/LYDMA transcription; evidence provided here indeed indicates clonal variation in IMP/LYDMA transcription. We propose to further analyze the structure and function of intracellular EBV terminal regions. First, the nature and location of clonal heterogeneity of terminal-region DNA will be further analyzed in our cell clones in tumor tissues. Second, quantitative estimates of clonal transcription of IMP/LYDMA will be obtained. Third, clonal variation in the chromatin structure of intracellular EBV terminal regions will be studied. Finally, members of one set of isogenic cell clones will be tested for their individual susceptibility to killing by autologous effector cells, in cytotoxicity assays; and these results will be correlated with the quantitative estimates of clonal transcription of IMP/LYDMA. The proposed studies utilize current findings to discern features of the EBV-terminal region which may be important in clonal dominance and tumorigenesis induced by EBV.