Institute of Virology, Hannover Medical School, 30625, Hannover, Germany.
Unit of Mycobacteriology, Institute of Tropical Medicine, 2000, Antwerp, Belgium.
Sci Rep. 2017 Nov 14;7(1):15588. doi: 10.1038/s41598-017-15783-x.
Cell rounding is a hallmark of the cytopathic effect induced by cytomegaloviruses. By screening a panel of deletion mutants of mouse cytomegalovirus (MCMV) a mutant was identified that did not elicit cell rounding and lacked the ability to form typical plaques. Altered cell morphology was assigned to the viral M25 gene. We detected an early 2.8 kb M25 mRNA directing the synthesis of a 105 kDa M25 protein, and confirmed that a late 3.1 kb mRNA encodes a 130 kDa M25 tegument protein. Virions lacking the M25 tegument protein were of smaller size because the tegument layer between capsid and viral envelope was reduced. The ΔM25 mutant did not provoke the rearrangement of the actin cytoskeleton observed after wild-type MCMV infection, and isolated expression of the M25 proteins led to cell size reduction, confirming that they contribute to the morphological changes. Yields of progeny virus and cell-to-cell spread of the ΔM25 mutant in vitro were diminished and replication in vivo was impaired. The identification of an MCMV gene involved in cell rounding provides the basis for investigating the role of this cytopathic effect in CMV pathogenesis.
细胞圆化是巨细胞病毒诱导的细胞病变效应的一个标志。通过筛选一组鼠巨细胞病毒（MCMV）缺失突变体，鉴定出一种不会引起细胞圆化且缺乏形成典型斑块能力的突变体。改变的细胞形态被归因于病毒的 M25 基因。我们检测到一个早期的 2.8kb M25 mRNA，指导合成一个 105kDa 的 M25 蛋白，并证实一个晚期的 3.1kb mRNA 编码一个 130kDa 的 M25 被膜蛋白。缺乏 M25 被膜蛋白的病毒粒子体积较小，因为衣壳和病毒包膜之间的被膜层减少了。ΔM25 突变体不会引起野生型 MCMV 感染后观察到的肌动蛋白细胞骨架的重排，并且单独表达 M25 蛋白会导致细胞大小减小，这证实了它们对形态变化的贡献。在体外，ΔM25 突变体的子代病毒产量和细胞间传播减少，体内复制受损。鉴定出一个参与细胞圆化的 MCMV 基因为研究这种细胞病变效应在 CMV 发病机制中的作用提供了基础。
