More importantly, this live attenuated virus provided effective protection when it was administered to birds before they had hatched.

更重要的是，这种减毒活病毒结种于未孵化的鸟类后可提供有效的预防。

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The virus was analyzed by the animal pathogenicity test, virus attenuation, protection of the attenuated virus and virulence return experiment.

对分离的痘病毒进行动物致病性试验、病毒分离传代和致弱试验、致弱毒保护力试验和返强试验。

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Most will be inactivated virus vaccines made in eggs, some will be killed virus vaccines made in cell cultures and a few will be live attenuated virus vaccines.

多数是在鸡胚中生产的灭活病毒疫苗，一些是在细胞培养基中生产的灭活疫苗，还有几个减活病毒疫苗。

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So, that was a naturally occurring attenuated virus that could be produced into a vaccine that didn't cause the disease.

因为天花病毒存在天然的衰减病毒,这种衰减病毒可以用来,直接生产不致病的疫苗

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He produced an oral polio vaccine from an attenuated virus.

他利用减毒病毒制得口服小儿麻痹症疫苗

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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

耶鲁公开课 - 生物医学工程探索课程节选