One is in the U.S.at the Centers for Disease Control, where there is a sample of variola, which is kept, you know, frozen on ice in a heavily guarded facility.

一个在美国的疾病控制中心,那有一支天花病毒的样本,冰冻后置于重重保护之下

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The virus enters the cell and it breaks down.

病毒进入细胞后分解

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So, you cross link all the proteins in the virus, and you make a particle that looks like a virus but it can't act like a virus any longer because it can't replicate.

当病毒中所有的蛋白质交联后,就得到了一种看上去像病毒,却无法致病的病毒,因为这种病毒不能进行复制

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This was not a naturally occurring attenuated virus as used in smallpox, but a virus that was attenuated in the laboratory, basically by propagating it in culture and looking for mutants that were formed as you propagated this virus under different experimental conditions.

这不是在制造天花疫苗时,使用的那种天然减毒病毒,而是一种在实验室中被人工弱化的病毒,基本上是通过在细胞中培养繁殖后,从这些培养出来的病毒中挑选出,不同实验环境下的变异体

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