Alonso M A, Carrasco L
J Gen Virol. 1982 Jun;60(Pt 2):315-25. doi: 10.1099/0022-1317-60-2-315.
The pattern of protein synthesis in HeLa cells simultaneously infected with encephalomyocarditis virus (EMCV) and Semliki Forest virus (SFV) has been analysed throughout the time course of the infection. The ratio of the picornavirus protein gamma versus the togavirus late protein C increased when the m.o.i. of EMCV was raised, and the ratio of C/gamma increased with higher multiplicities of SFV. Under some conditions, the co-infected cells simultaneously synthesized the picornavirus and togavirus proteins, and the cells exclusively translated the capped 26S mRNA from SFV at the end of the co-infection experiment. The influence of the time of addition of the second virus on the relative translation of the capped and uncapped mRNAs was also studied. When HeLa cells were co-infected with 5 p.f.u./cell of EMCV and 200 p.f.u./cell of SFV, only the synthesis of SFV proteins was apparent, whereas if SFV was added 1 to 3 h later during the course of EMCV infection the cells synthesized picornavirus and togavirus proteins. If the cells were superinfected with SFV 1 h after EMCV addition, host protein synthesis was drastically inhibited after 3 h of EMCV infection. By 5 h post-infection both kinds of virus proteins were synthesized and at 7 h post-infection the cells preferentially translated the capped 26S mRNA from SFV. If cells were first infected with SFV (10 p.f.u./cell) and co-infected or superinfected at 1 h with EMCV (50 p.f.u./cell), shut-off of host protein synthesis occurred 3 h after infection and the cells synthesized both kinds of virus proteins. However, 9 h after infection the cells synthesized SFV proteins only. When double-infected HeLa cells were placed in a hypotonic medium, they mainly synthesized the togavirus late proteins, whereas under hypertonic conditions, they translated the picornavirus RNA exclusively. These results suggest that the two kinds of mRNAs (SFV 26S mRNA and EMCV 35S mRNA) are present in the infected cells and that the relative translation of each of them depends on the external ionic conditions.
在整个感染过程中，对同时感染脑心肌炎病毒（EMCV）和辛德毕斯病毒（SFV）的HeLa细胞中的蛋白质合成模式进行了分析。当提高EMCV的感染复数（m.o.i.）时，小RNA病毒蛋白γ与披膜病毒晚期蛋白C的比例增加，而随着SFV感染复数的增加，C/γ比例也增加。在某些条件下，共感染的细胞同时合成小RNA病毒和披膜病毒蛋白，并且在共感染实验结束时，细胞仅翻译来自SFV的加帽26S mRNA。还研究了添加第二种病毒的时间对加帽和未加帽mRNA相对翻译的影响。当HeLa细胞以每细胞5个空斑形成单位（p.f.u.）的EMCV和每细胞200个p.f.u.的SFV共感染时，仅SFV蛋白的合成明显，而如果在EMCV感染过程中1至3小时后添加SFV，则细胞合成小RNA病毒和披膜病毒蛋白。如果在添加EMCV后1小时用SFV对细胞进行超感染，在EMCV感染3小时后宿主蛋白合成受到强烈抑制。感染后5小时，两种病毒蛋白都被合成，并且在感染后7小时，细胞优先翻译来自SFV的加帽26S mRNA。如果细胞首先用SFV（每细胞10个p.f.u.）感染，并在1小时时用EMCV（每细胞50个p.f.u.）共感染或超感染，宿主蛋白合成在感染后3小时发生关闭，并且细胞合成两种病毒蛋白。然而，感染后9小时，细胞仅合成SFV蛋白。当双重感染的HeLa细胞置于低渗培养基中时，它们主要合成披膜病毒晚期蛋白，而在高渗条件下，它们仅翻译小RNA病毒RNA。这些结果表明，两种mRNA（SFV 26S mRNA和EMCV 35S mRNA）存在于感染细胞中，并且它们各自的相对翻译取决于外部离子条件。
