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

马立克氏病病毒(MDV)是一种能引起鸡淋巴增生性疾病的禽疱疹病毒。MDV DNA 6amHI-H区1.8kb基因的表达可能与MDV致瘤性的维持有关。然而，1.8kb基因功能的直接证据一直缺乏。我们利用与1.8kb基因互补的寡核苷酸研究了1.8kb基因在肿瘤发生中的作用。虽然MDV潜伏感染的维持似乎涉及到调节病毒转录的机制，但目前还不清楚哪些因素负责转录控制。我们研究了MDV DNA的初级和高阶结构是否与淋巴母细胞系中MDV基因组转录的抑制有关。与MDV DNA 6amHI-H区1.8kb基因剪接供体序列互补的寡核苷酸可抑制淋巴母细胞系的增殖。MDCC-MSBI(MSBI)。但不包括禽淋巴白血病来源的淋巴母细胞系LSCC-BK3。软琼脂中的克隆形成也被反义寡核苷酸处理的MSBI细胞所抑制。因此。1.8kb基因家族的表达与转化的MDV来源的淋巴母细胞的致瘤状态的维持直接相关。仅在不产毒细胞系MDCC-RPI(RPI)的MDV DNA中发现了包含MDV DNA复制起点的区域两侧的唯一片段。复制起始区附近DNA结构的改变可能与MDV在RPI中的生产力丧失有关。在MSBI和RPI中，潜伏的MDV基因组折叠成核小体结构。MDV基因组转录活跃区和非活跃区在核小体模式方面没有差异。

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.