Bablanian R, Esteban M, Baxt B, Sonnabend J A
J Gen Virol. 1978 Jun;39(3):391-402. doi: 10.1099/0022-1317-39-3-391.
The mechanism of vaccinia virus-induced inhibition of protein synthesis was studied in LLC-MK2, HeLa and L cells. Removal of cycloheximide (300 microgram/ml) from cells infected at a multiplicity of infection (m.o.i.) of 300 particles/cell at 4 h after infection resulted in the resumption of both host and virus protein synthesis in LLC-MK2 cells, but not in HeLa and L cells. In order to determine whether virus-induced RNA synthesis, which occurs in infected cells in the presence of cycloheximide, is related to the inhibition of protein synthesis, (cut-off), the rate of virus-induced RNA synthesis in the presence of cycloheximide was measured in all three cell types. In L cells and HeLa cells the rate of virus-induced RNA synthesis increased with time, whereas in LLC-MK2 cells it remained constant for at least 4 h. However, when higher multiplicities (900 and 2700 particles/cell) were used to infect LLC-MK2 cells, the rate of RNA synthesis in the presence of cycloheximide did increase with time and was greater at the higher multiplicity. Under these conditions there was a direct relationship between the extent of virus RNA synthesis and the degree of cut-off after the removal of cycloheximide. In HeLa and L cells infected at 300 particles/cell, the longer the exposure to cycloheximide, the greater was the cut-off observed upon removal of the drug. As was the case the LLC-MK2 cells, there was a direct relationship between the rate of RNA synthesis and the degree of inhibition of protein synthesis. Since virus-induced RNA synthesis occurs in the presence of cycloheximide, the effects of actinomycin D and cordycepin on host polypeptide synthesis were tested. Inhibition of host cell protein synthesis was virtually abolished when HeLA cells were infected in the presence of cordycepin (50 and 25 microgram/ml) or actinomycin D (20 microgram/ml). These results indicate that, as the rate of virus-induced RNA synthesis increased, regardless of the type of cell used, protein synthesis was inhibited at earlier times and to a greater extent. These observations are consistent with the hypothesis that the cut-off phenomenon is related to the synthesis of an early virus-induced RNA(s).
在LLC-MK2、HeLa和L细胞中研究了痘苗病毒诱导的蛋白质合成抑制机制。在感染后4小时，从以感染复数（m.o.i.）为300个颗粒/细胞感染的细胞中去除环己酰亚胺（300微克/毫升），LLC-MK2细胞中的宿主和病毒蛋白质合成均恢复，但HeLa和L细胞中未恢复。为了确定在环己酰亚胺存在下感染细胞中发生的病毒诱导的RNA合成是否与蛋白质合成抑制有关，（截断），在所有三种细胞类型中测量了环己酰亚胺存在下病毒诱导的RNA合成速率。在L细胞和HeLa细胞中，病毒诱导的RNA合成速率随时间增加，而在LLC-MK2细胞中至少4小时保持恒定。然而，当使用更高的感染复数（900和2700个颗粒/细胞）感染LLC-MK2细胞时，环己酰亚胺存在下的RNA合成速率确实随时间增加，且在更高的感染复数下更大。在这些条件下，病毒RNA合成程度与去除环己酰亚胺后的截断程度之间存在直接关系。在以300个颗粒/细胞感染的HeLa和L细胞中，暴露于环己酰亚胺的时间越长，去除药物后观察到的截断程度越大。与LLC-MK2细胞情况一样，RNA合成速率与蛋白质合成抑制程度之间存在直接关系。由于病毒诱导的RNA合成在环己酰亚胺存在下发生，因此测试了放线菌素D和虫草素对宿主多肽合成的影响。当HeLA细胞在虫草素（50和25微克/毫升）或放线菌素D（20微克/毫升）存在下感染时，宿主细胞蛋白质合成的抑制几乎被消除。这些结果表明，随着病毒诱导的RNA合成速率增加，无论使用何种细胞类型，蛋白质合成在更早的时间受到更大程度的抑制。这些观察结果与截断现象与早期病毒诱导的RNA合成有关的假设一致。
