Reduced precore transcription and enhanced core-pregenome transcription of hepatitis B virus DNA after replacement of the precore-core promoter with sequences associated with e antigen-seronegative persistent infections
Reduced precore transcription and enhanced core-pregenome transcription of hepatitis B virus DNA after replacement of the precore-core promoter with sequences associated with e antigen-seronegative persistent infections
复制标题
DOI：
10.1006/viro.1996.0655
复制
发表时间：
1996-12-15
期刊：
影响因子：
3.7
通讯作者：
Mayumi, M
中科院分区：
文献类型：
--
作者：
Moriyama, K;Okamoto, H;Mayumi, M
在暴发性乙型肝炎以及 HBeAg 血清阴性持续感染中已检测到前 C-C 启动子中含有核苷酸改变的乙型肝炎病毒变体。然而，尚未证明 preC-C 启动子中具有核苷酸改变的变体会导致各种疾病。我们用最常见的自然发生的突变形式替换野生型基因组的 preC-C 启动子区域，并将其引入 HepG2 细胞中。具有 A1762T 和 G1764A 取代共存的突变体产生的 HBeAg 水平不到野生型的五分之一。相反，突变体产生的核心颗粒抗原是原来的 2.4 倍，并表现出高复制表型。与野生型相比，RNase 保护和定量 5' RACE 显示突变体的前 C 转录本减少了 16 至 32 倍，C 转录本诱导增加了 4 倍。突变体的前C转录本具有比witd型更异质的5'端。然而，突变并没有改变 C 转录的起始位点。当启动子区域被克隆到 CAT 质粒中时，突变对 preC 和 C 启动子活性产生双重影响，分别降低和增加。这些结果表明，这些突变导致 HBeAg 产生减少以及复制和核心产生增强。对具有任一单点突变的回复体的分析表明，1762处的T对于突变表型至关重要。 (C) 1996 学术出版社
Hepatitis B virus variants harboring nucleotide alterations in the preC-C promoter have been detected in fulminant hepatitis B as well as in HBeAg-seronegative persistent infection. However, it has not been demonstrated that variants with nucleotide alterations in the preC-C promoter cause various disease slates, We replaced the preC-C promoter region of a wild-type genome with the most frequent naturally occurring mutated form and introduced it into HepG2 cells. The mutant with coexisting A1762T and G1764A substitutions produced less than one-fifth of the wild-type level of HBeAg. Conversely, the mutant generated 2.4 times more core particle antigen and showed a high-replicator phenotype. RNase protection and quantitative 5' RACE showed a 16- to 32-fold reduction of preC transcripts and a 4-fold induction of C transcripts of the mutant compared to wild-type. The preC transcript of the mutant had a more heterogeneous 5' end than that of the witd-type. However, the mutations did not alter the initiation sites of C transcription. When the promoter region was cloned into CAT plasmids, the mutations had dual effects on preC and C promoter activities, decreasing and increasing them, respectively. These results suggest that these mutations are responsible for the reduced HBeAg production as well as the enhanced replication and core production. Analysis of revertants with either single point mutation showed that T at 1762 is critical for the mutant phenotype. (C) 1996 Academic Press, Inc.