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1·On rare occasions, avian influenza viruses have crossed the species barrier to infect humans.

在极少数情况下，禽流感病毒已跨越物种屏障，感染人类。

2·Mankind, it seems, was just unlucky that this virus made the leap across the species barrier.

似乎这种病毒得以跨越物种的障碍传染到人类身上仅仅是出于人类的不幸。

3·Pigs are flu sponges, capable of contracting both bird and human viruses that can jump across the species barrier, Richt says.

里希特说，猪是流感海绵，能够跨跃物种界线吸取人类和禽类的流感病毒。

4·Avian influenza viruses are highly species-specific, but have, on rare occasions, crossed the species barrier to infect humans.

禽流感病毒具有高度物种特异性，但偶尔也跨越物种屏障，感染人类。

5·Some of these AI viruses have also been reported to cross the species barrier and cause disease or subclinical infections in humans and other mammals.

也有报告称，某些禽流感病毒跨越物种界限传播，并导致人类和其他哺乳动物患病或亚临床感染。

6·The test tube is obviously an unnatural situation, but it shows that prions can leap the species barrier without the aid of any other infectious agent.

显然在试管里的情况是一种非自然状态，但是这项研究表明朊蛋白能在不借助于任何其它传染媒介的情况下跨越物种障碍。

7·Although swine influenza viruses are normally species specific and only infect pigs, they do sometimes cross the species barrier to cause disease in humans.

这能导致一个流感病毒包含许多来源的基因，称为重组病毒。一般来说，猪流感病毒存在种属特异性、只感染猪，但有时确实能跨越种群屏障引起人类发病。

8·Population growth also puts people in close proximity to domestic animals, creating evolutionary pressures and opportunities for pathogens to jump the species barrier.

人口增长还导致人们与家禽比邻而居，造成了病原体跨越种属屏障的进化压力和机会。

9·Of the few avian influenza viruses that have crossed the species barrier to infect humans, H5N1 has caused the largest number of cases of severe disease and death in humans.

在跨越物种屏障感染人类的若干禽流感病毒中，H5N1导致的人类重症病例和死亡数目最多。

10·No one now knows how easy it would be to turbo-charge an existing human pathogen, or take one that infects another type of animal and assist its passage over the species barrier.

现在没人知道激发一种既存的人体病菌有多么容易，不知道使病菌传染给另一种动物，帮助其跨越物种界限而传播有多么容易。