Nicholas J, Zong J C, Alcendor D J, Ciufo D M, Poole L J, Sarisky R T, Chiou C J, Zhang X, Wan X, Guo H G, Reitz M S, Hayward G S
Molecular Virology Laboratories, Oncology Center, Johns Hopkins School of Medicine, Baltimore, MD, USA.
J Natl Cancer Inst Monogr. 1998(23):79-88. doi: 10.1093/oxfordjournals.jncimonographs.a024179.
Strong serologic and molecular probe correlations indicate that the newly discovered gamma herpesvirus KSHV or HHV8 is the likely etiologic agent of all forms of Kaposi's sarcoma as well as BCBL/PEL and MCD in patients with acquired immunodeficiency syndrome (AIDS). Two large segments of HHV8 DNA from an AIDS-associated BCBL tumor covering genomic positions 0-52 kilobase [kb] and 108-140 kb have been cloned, mapped, and partially sequenced. Our studies have focused on novel viral proteins encoded within a 13-kb divergent locus (DL-B) by nine captured homologues of cellular genes, including vIL-6, vDHFR, vTS, vBcl-2, three C-C beta chemokines (vMIP-1A, vMIP-1B, and vBCK), and two LAP/PHD subclass zinc finger proteins (IE1A and IE1B). The HHV-8 vIL-6, vDHFR, vTS, and vBcl-2 proteins have all been shown to be active in a variety of appropriate functional assays, and transcripts from vIL-6, vMIP-1B, vIE1-A, vIE1-B, and vDHFR genes are all expressed as abundant single messenger RNA species after butyrate or phorbol ester (TPA) induction of the lytic cycle in HHV8-positive BCBL cell lines. All of these genes lie within a divergent transcriptional domain that contains a single central enhancer and associated untranslated leader region plus seven distinct proximal promoters, some of which are negatively regulated through AP-1 and ZRE motifs by the EBV ZTA transactivator. This region also encompasses a predicted complex oriLyt domain of 1050 bp that is duplicated in inverted orientation adjacent to the T0.7 latency RNA in another large divergent locus (DL-E). We have previously described three distinct subtypes of the HHV8 genome that differ by 1.0%-1.5% at the nucleotide level within the ORF26 and ORF75 genes. Certain strains or clades appear to have preferential geographic distributions, but it is not known as yet whether there are any specific disease associations. Interestingly, the A, B, and C subtypes of HHV-8 also proved to differ dramatically in coding content at both the extreme left and right ends of the unique segment of the genome as well as in the positions of the junctions with the terminal repeats. On the left-hand side, the receptor-like ORF-K1 protein is highly variable with A-strain subtypes displaying 15% amino acid differences from C strains and up to 30% differences from B strains. On the right-hand side, two unrelated alternative types of the putative multiple membrane spanning ORF-K15 protein are found.
强大的血清学和分子探针相关性表明，新发现的γ疱疹病毒KSHV或HHV8可能是获得性免疫缺陷综合征（AIDS）患者中所有形式的卡波西肉瘤以及BCBL/PEL和MCD的病原体。来自与艾滋病相关的BCBL肿瘤的两段大的HHV8 DNA片段，覆盖基因组位置0至52千碱基[kb]和108至140 kb，已被克隆、定位并部分测序。我们的研究集中在一个13 kb的差异位点（DL-B）内由九个捕获的细胞基因同源物编码的新型病毒蛋白，包括vIL-6、vDHFR、vTS、vBcl-2、三种C-Cβ趋化因子（vMIP-1A、vMIP-1B和vBCK）以及两种LAP/PHD亚类锌指蛋白（IE1A和IE1B）。HHV-8的vIL-6、vDHFR、vTS和vBcl-2蛋白在各种适当的功能试验中均显示有活性，并且在丁酸盐或佛波酯（TPA）诱导HHV8阳性BCBL细胞系的裂解周期后，vIL-6、vMIP-1B、vIE1-A、vIE1-B和vDHFR基因的转录本均以丰富的单信使RNA形式表达。所有这些基因都位于一个差异转录域内，该域包含一个单一的中央增强子和相关的非翻译前导区以及七个不同的近端启动子，其中一些通过EBV ZTA反式激活因子的AP-1和ZRE基序受到负调控。该区域还包含一个预测的1050 bp的复杂oriLyt域，该域在另一个大的差异位点（DL-E）中以反向重复的形式与T0.7潜伏RNA相邻。我们之前描述了HHV8基因组的三种不同亚型，它们在ORF26和ORF75基因的核苷酸水平上相差1.0%-1.5%。某些菌株或进化枝似乎具有优先的地理分布，但目前尚不清楚是否存在任何特定的疾病关联。有趣的是，HHV-8的A、B和C亚型在基因组独特片段的最左端和最右端的编码内容以及与末端重复序列的连接处位置也有显著差异。在左侧，受体样ORF-K1蛋白高度可变，A株亚型与C株显示15%的氨基酸差异，与B株高达30%的差异。在右侧，发现了两种不相关的推定跨膜多聚体ORF-K15蛋白类型。
