The way the body recognises an infection is by examining molecules from the infectious agent.

身体对外物感染的识别是通过检测感染性外物的分子来实现的。

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I reckon a lot of these mysterious chronic diseases are related to some infectious agent that's been a trigger.

我猜测很多神秘的慢性疾病都和一些感染源的激发有关。

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Virus: Microscopic, simple infectious agent that can multiply only in living cells of animals, plants, or bacteria.

病毒：微小、简单的传染因子，仅在动物、植物、细菌的活细胞中能够繁殖。

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Usually it's done by taking all or part of the infectious agent, and showing them to your immune system in some way.

通常它会带着全部或部分抗原介质,并以某种方式呈递给你的免疫系统

耶鲁公开课 - 生物医学工程探索课程节选

So, it first infects you because you breathe in some of the infectious agent.

所以,只要吸入病原体,你就会被感染

耶鲁公开课 - 生物医学工程探索课程节选

Usually it involves pieces of the infectious agent itself, to cause that engagement.

通常疫苗自身也包含部分传染性介质,以便达成匹配

耶鲁公开课 - 生物医学工程探索课程节选

Some scientists think it's caused by an infectious agent, such as a virus.

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The infectious agent takes at least six to eight years to cause symptoms in cows, meaning that the infected cow was likely spreading the disease during that time.

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"Currently, we have identified no infectious agent common to all of the cases, " the statement said, adding that no evidence exists that the cases were caused by exposure to chemical or biological weapons, SARS or environmental toxins.

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