Attenuation of Tick-Borne Encephalitis Virus Using Large-Scale Random Codon Reencoding
Attenuation of Tick-Borne Encephalitis Virus Using Large-Scale Random Codon Reencoding
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DOI：
10.1371/journal.ppat.1004738
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发表时间：
2015-03-01
期刊：
影响因子：
6.7
通讯作者：
de Lamballerie, Xavier
中科院分区：
文献类型：
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作者：
de Fabritus, Lauriane;Nougairede, Antoine;de Lamballerie, Xavier
大规模密码子重新编码（即引入大量同义突变）是一种产生减毒病毒的新方法。在这里，它被应用于致病性黄病毒、蜱传脑炎病毒（TBEV），这种病毒会在欧洲和亚洲森林地区的人类中引起发热性疾病和脑炎。使用Oshima 5-10毒株（“野生型病毒”）的感染性克隆，通过随机引入273个同义突变（“重新编码病毒”）来修改位于NS5编码区的1.4kb盒。虽然重新编码病毒的细胞内复制适应性仅略有降低，但重新编码病毒在非致命性脑炎实验室小鼠模型中表现出减毒表型。腹膜内接种 2.10(5) 或 2.10(6) TCID50 的病毒后，与野生型病毒相比，病毒血症的频率、神经毒力（通过体重减轻和症状出现来测量）和神经侵袭性（在大脑中检测到病毒）显着降低。被野生型病毒或重新编码病毒感染的小鼠产生了相当数量的中和抗体，攻击实验的结果表明，先前感染重新编码病毒的小鼠受到保护，免受野生型病毒的后续感染。这证明哺乳动物物种在用衍生的随机重新编码毒株免疫后可以免受有毒野生型正链RNA病毒的感染。我们的结果表明，随机密码子重新编码可能是产生针对致病性黄病毒的减毒活疫苗候选物的简单而有效的方法。
Large-scale codon re-encoding (i.e. introduction of a large number of synonymous mutations) is a novel method of generating attenuated viruses. Here, it was applied to the pathogenic flavivirus, tick-borne encephalitis virus (TBEV) which causes febrile illness and encephalitis in humans in forested regions of Europe and Asia. Using an infectious clone of the Oshima 5-10 strain ("wild-type virus"), a cassette of 1.4kb located in the NS5 coding region, was modified by randomly introducing 273 synonymous mutations ("re-encoded virus"). Whilst the in cellulo replicative fitness of the re-encoded virus was only slightly reduced, the re-encoded virus displayed an attenuated phenotype in a laboratory mouse model of non-lethal encephalitis. Following intra-peritoneal inoculation of either 2.10(5) or 2.10(6) TCID50 of virus, the frequency of viraemia, neurovirulence (measured using weight loss and appearance of symptoms) and neuroinvasiveness (detection of virus in the brain) were significantly decreased when compared with the wild-type virus. Mice infected by wildtype or re-encoded viruses produced comparable amounts of neutralising antibodies and results of challenge experiments demonstrated that mice previously infected with the re-encoded virus were protected against subsequent infection by the wild-type virus. This constitutes evidence that a mammalian species can be protected against infection by a virulent wild-type positive-stranded RNA virus following immunisation with a derived randomly reencoded strain. Our results demonstrate that random codon re-encoding is potentially a simple and effective method of generating live-attenuated vaccine candidates against pathogenic flaviviruses.