After plant infect with the virus, a photosynthetic rate of leaf of different leaf-age will lower.

植株感染病毒后，不同叶龄的叶片光合速率都会降低。

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Meanwhile, the deadliest strains of the virus perished with their hosts as natural selection favored strains that could infect hosts but not kill them.

同时，由于自然选择更倾向于选择那些能够感染宿主但不致其死亡的病毒，这种致命病毒便随着宿主的死亡而消失。

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Scientists are really interested in this idea that if you infect people with the virus, everybody will get infected, but only 75% of people will actually come down with the cold.

如果用感冒病毒感染人群，人人都会被感染，但只有75%的人会真正患上感冒，科学家对此点十分感兴趣。

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In August of nineteen hundred, the researchers began to raise mosquitoes and infect them with the virus.

VOA: special.2010.05.18

You infect them with the virus, and you let the cells, in culture, produce the virus.

再用病毒感染它们,使培养基中的细胞产生病毒

耶鲁公开课 - 生物医学工程探索课程节选

In August of 1900, the researchers began to raise mosquitoes and infect them with the virus.

VOA: special.2009.01.27

Next year, Professor John Oxford, an expert in virology from Queen Mary's School of Medicine and Dentistry, in London, will lock volunteers in a hotel for a week, deliberately infect some with the flu virus, and wait to see what happens.

BBC: Colds and flu remain mysterious

The therapy, developed by UniQure, uses a virus to infect muscle cells with a working copy of the gene.

BBC: Gene therapy: Glybera approved by European Commission

"To start with, we'll take 15 volunteers, with no immunity to the particular flu virus and infect five of them, " he said.

BBC: Colds and flu remain mysterious