Rational Design of a Flavivirus Vaccine by Abolishing Viral RNA 2′-O Methylation
Rational Design of a Flavivirus Vaccine by Abolishing Viral RNA 2′-O Methylation
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DOI：
10.1128/jvi.02806-12
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发表时间：
2013-05-01
影响因子：
5.4
通讯作者：
Shi, Pei-Yong
中科院分区：
文献类型：
--
作者：
Li, Shi-Hua;Dong, Hongping;Shi, Pei-Yong
在细胞质中复制的病毒不能进入宿主的核帽机制。这些病毒已经进化出病毒甲基转移酶以甲基化其RNA的N-7和2 '-O帽;或者，它们“抢夺”宿主mRNA帽以形成病毒RNA的5'端。病毒RNA帽的2 '-O甲基化的功能是模仿细胞mRNA并逃避宿主先天免疫限制。2 '-O甲基化缺陷的细胞质病毒是复制性的，但其病毒RNA缺乏2'-O甲基化，并被宿主免疫应答识别和消除。这样的突变病毒可以被合理地设计为减毒活疫苗。在这里，我们使用日本脑炎病毒（JEV），一种重要的蚊媒黄病毒，以证明这种新的疫苗概念。我们发现JEV甲基转移酶负责N-7和2 '-O帽甲基化以及逃避宿主先天免疫应答。2 '-O甲基化完全缺陷的重组病毒在细胞培养物中传代>30天后是稳定的。该突变病毒在小鼠中减毒，引发了强大的体液和细胞免疫应答，并在体内保留了工程突变。单剂量免疫诱导小鼠对JEV毒株致死性攻击的完全保护。从机制上讲，减毒表型归因于突变病毒对干扰素和IFIT蛋白的抗病毒作用的敏感性增强。总的来说，结果证明了使用2 '-O甲基化缺陷病毒作为疫苗方法的可行性;这种疫苗方法应该适用于编码其自身病毒2'-O甲基转移酶的其他黄病毒和非黄病毒。
Viruses that replicate in the cytoplasm cannot access the host nuclear capping machinery. These viruses have evolved viral methyltransferase(s) to methylate N-7 and 2'-O cap of their RNA; alternatively, they "snatch" host mRNA cap to form the 5' end of viral RNA. The function of 2'-O methylation of viral RNA cap is to mimic cellular mRNA and to evade host innate immune restriction. A cytoplasmic virus defective in 2'-O methylation is replicative, but its viral RNA lacks 2'-O methylation and is recognized and eliminated by the host immune response. Such a mutant virus could be rationally designed as a live attenuated vaccine. Here, we use Japanese encephalitis virus (JEV), an important mosquito-borne flavivirus, to prove this novel vaccine concept. We show that JEV methyltransferase is responsible for both N-7 and 2'-O cap methylations as well as evasion of host innate immune response. Recombinant virus completely defective in 2'-O methylation was stable in cell culture after being passaged for >30 days. The mutant virus was attenuated in mice, elicited robust humoral and cellular immune responses, and retained the engineered mutation in vivo. A single dose of immunization induced full protection against lethal challenge with JEV strains in mice. Mechanistically, the attenuation phenotype was attributed to the enhanced sensitivity of the mutant virus to the antiviral effects of interferon and IFIT proteins. Collectively, the results demonstrate the feasibility of using 2'-O methylation-defective virus as a vaccine approach; this vaccine approach should be applicable to other flaviviruses and nonflaviviruses that encode their own viral 2'-O methyltransferases.