Division of Virology, National Cancer Center Research Institute, Tsukiji, Chuo-ku, Tokyo, Japan.
J Virol. 2012 Mar;86(6):3276-83. doi: 10.1128/JVI.06450-11. Epub 2012 Jan 11.
Papillomavirus genomes are thought to be amplified to about 100 copies per cell soon after infection, maintained constant at this level in basal cells, and amplified for viral production upon keratinocyte differentiation. To determine the requirement for E1 in viral DNA replication at different stages, an E1-defective mutant of the human papillomavirus 16 (HPV16) genome featuring a translation termination mutation in the E1 gene was used. The ability of the mutant HPV16 genome to replicate as nuclear episomes was monitored with or without exogenous expression of E1. Unlike the wild-type genome, the E1-defective HPV16 genome became established in human keratinocytes only as episomes in the presence of exogenous E1 expression. Once established, it could replicate with the same efficiency as the wild-type genome, even after the exogenous E1 was removed. However, upon calcium-induced keratinocyte differentiation, once again amplification was dependent on exogenous E1. These results demonstrate that the E1 protein is dispensable for maintenance replication but not for initial and productive replication of HPV16.
乳头瘤病毒基因组在感染后不久被认为会扩增到每个细胞约 100 个拷贝，在基底层保持恒定水平，并在角质形成细胞分化时扩增以进行病毒产生。为了确定 E1 在不同阶段病毒 DNA 复制中的要求，使用了一种人乳头瘤病毒 16（HPV16）基因组的 E1 缺陷突变体，该突变体在 E1 基因中具有翻译终止突变。使用或不使用外源性 E1 表达来监测突变 HPV16 基因组作为核附加体进行复制的能力。与野生型基因组不同，E1 缺陷 HPV16 基因组仅在外源 E1 表达存在的情况下才能作为附加体在人角质形成细胞中建立。一旦建立，即使去除外源性 E1，它也可以以与野生型基因组相同的效率进行复制。然而，在钙诱导的角质形成细胞分化时，再次扩增仍然依赖于外源性 E1。这些结果表明，E1 蛋白对于 HPV16 的维持复制不是必需的，但对于初始和有效复制是必需的。
