We know now that it's caused by a related virus, called vaccinia, remember the virus that causes smallpox is called variola.

我们现在知道这病由一种相关的病毒引起,这种病毒叫牛痘病毒,想想天花病毒也被叫做牛痘病毒

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Remember that the lucky thing about the smallpox vaccine was that a naturally occurring attenuated form of the smallpox virus variola called vaccinea was found.

对于天花病毒来说,幸运的是,存在一种自然发生的,被称作痘苗病毒的,天花病毒的衰减疫苗

耶鲁公开课 - 生物医学工程探索课程节选

The name of the virus is variola.

病毒的名字叫天花病毒

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Smallpox is a virus called variola, it's a virus that contains DNA.

天花是病毒引起的,这种病毒含DNA

耶鲁公开课 - 生物医学工程探索课程节选