Investigation of the genes associated with tumorigenicity of Marek's disease virus.

马立克病病毒（Marek’s disease virus， MDV）是一种引起鸡淋巴细胞增生性疾病的禽疱疹病毒。有研究表明，维持致瘤性可能与MDV DNA 6amHI-H区1.8 kb基因的表达有关。然而，1.8 kb基因功能的直接证据一直缺乏。我们利用与1.8 kb基因互补的寡核苷酸检测了1.8 kb基因在致瘤性中的作用。尽管MDV潜伏感染的维持似乎涉及调节病毒转录的机制，但尚不清楚哪些因素负责转录控制。我们研究了淋巴母细胞样细胞系中MDV DNA的初级和高级结构是否与MDV基因组转录的抑制相关。从MDV DNA的6amHI-H区产生的1.8 kb基因剪接供体序列互补的寡核苷酸抑制淋巴母细胞样细胞系的增殖。MDCC-MSBI (MSBI)。但禽淋巴样白血病衍生的淋巴母细胞样细胞系LSCC-BK3没有。用反义寡核苷酸处理MSBI细胞也能抑制软琼脂中的菌落形成。因此。1.8 kb基因家族的表达与转化的mdv源性淋巴母细胞样细胞的致瘤状态的维持直接相关。仅在非产病毒细胞系MDCC-RPI （RPI）的MDV DNA中发现了该区域两侧包含假定的MDV DNA复制起源的独特片段。复制起始区附近DNA结构的变化可能与RPI中MDV生产力的丧失有关。潜伏的MDV基因组在MSBI和RPI中折叠成核小体结构。在核小体模式方面，MDV基因组转录活性区和非活性区之间没有差异。

Marek's disease virus (MDV) is an avian herpesvirus which induces lymphoproliferative disease in chickens. It has been suggested that maintenance of tumorigenicity might be associated with the expression of the 1.8 kb gene from 6amHI-H region of MDV DNA. However, direct proof of the function of the 1.8 kb gene has been lacking. We examined the role of the 1.8 kb gene in tumorigenicity, using oligonucleotides complementary to the 1.8 kb gene. Although maintenance of latent infection of MDV seems to involve mechanisms regulating viral transcription, it is not clear which factors are responsible for transcriptional control. We investigated whether primary and higher order structures of MDV DNA are correlated with the repression of transcription from MDV genome in lymphoblastoid cell lines.1. An oligonucleotide complementary to the splice donor sequence of the 1.8 kb gene produced from 6amHI-H region of MDV DNA inhibited the proliferation of lymphoblastoid cell line. MDCC-MSBI(MSBI). but not that of the avian lymphoid leukosis-derived lymphoblastoid cell line, LSCC-BK3. Colony formation in soft agar was also inhibited by treatment of MSBI cells with antisense oligonucleotide. Thus. expression of the 1.8 kb gene family is directly associated with maintenance of tumorigenic state of transformed MDV-derived lymphoblastoid cells.2. The unique fragment flanking the region which contains the putative replication origin of MDV DNA was found in only MDV DNA from virus-nonproducing cell iine MDCC-RPI (RPI). The change in DNA structure near the region of replication origin might be associated with the loss of MDV productivity in RPI. The latent MDV genome are folded into nucleosomal structures in MSBI and RPI. There was no difference between transcriptionally active and inactive regions of MDV genome with regard to nucleosomal patterns.