Human herpesvirus 6A (HHV‐6A) is a member of the genus Roseolovirus and the subfamily Betaherpesvirinae. It is similar to and human cytomegalovirus (HCMV). HHV‐6A encodes a 41 kDa nuclear phosphoprotein, U27, which acts as a processivity factor in the replication of the viral DNA. HHV‐6A U27 has 43% amino acid sequence homology with HCMV UL44, which is important for DNA replication. A previous study on HHV‐6A U27 revealed that it greatly increases the in vitro DNA synthesis activity of HHV‐6A DNA polymerase. However, the role of U27 during the HHV‐6A virus replication process remains unclear. In this study, we constructed a U27‐deficient HHV‐6A mutant (HHV‐6ABACU27mut) with a frameshift insertion at the U27 gene using an HHV‐6A bacterial artificial chromosome (BAC) system. Viral reconstitution from the mutant BAC DNA was not detected, in contrast to the wild type and the revertant from the U27 mutant. This suggests that U27 plays a critical role in the life cycle of HHV‐6A.

中文翻译：

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人疱疹病毒6A U27在病毒传播中起着至关重要的作用。

人疱疹病毒6A（HHV-6A）是迷迭香病毒属和Betaherpesvirinae家族的成员。它与人类巨细胞病毒（HCMV）相似。HHV-6A编码一个41 kDa的核磷蛋白U27，在病毒DNA复制中起着持续性作用。HHV-6A U27与HCMV UL44具有43％的氨基酸序列同源性，这对DNA复制很重要。先前对HHV-6A U27的研究表明，它大大增加了体外HHV-6A DNA聚合酶的DNA合成活性。但是，U27在HHV-6A病毒复制过程中的作用仍不清楚。在这项研究中，我们使用HHV-6A细菌人工染色体（BAC）系统构建了一个U27缺陷型HHV-6A突变体（HHV-6ABACU27mut），该突变体在U27基因处插入了移码。与野生型和U27突变体的回复子相比，突变BAC DNA的病毒未检出。这表明U27在HHV-6A的生命周期中起着至关重要的作用。