| 1. | That animal diseases jump the species barrier from time to time is well understood
动物疾病跨越物种进行传播已不是新鲜事。 |
| 2. | Experts believe that human infections can occur because the h5 strain under some circumstances is able to jump the species barrier
菌株在一定环境下能越过种属间的屏障。 |
| 3. | Although natural hosts are birds , the avian influenza viruses are known to cross species barriers to infect other mammals , including humans
尽管鸟类是自然宿主，但禽流感病毒能够跨物种感染其它哺乳动物包括人类。 |
| 4. | Specific mutations in a iral protein , the polymerase , contribute to the ability of the bird irus to jump the species barrier to humans
病毒蛋白质的特有的突变和多聚酶促成了禽类病毒跨越种间障碍传播到人类的能力 |
| 5. | 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
在少数能够跨越种属屏障感染人的病毒株中， h5n1在人群中引起的病例数最多。 |
| 6. | It sparked worldwide concern when the deadly h5n1 strain of virus crossed the species barrier and claimed human victims in isolated , but nonetheless headline grabbing cases
菌株可以越过种属间的屏障，这引起了全球关注，也造成人类的偶然感染，但媒体并没有捕捉到具体的病例。 |
| 7. | Experts also fear the close contact between humans and wild animals in such markets could help unknown viruses jump the species barrier and spark deadly epidemics , such as the sars outbreak earlier this year
专家也对这种人类与野生动物在市场上如此接触表示担忧，这种密切接触会使不知名的病毒跳过物种间的障碍，导致致命的流行病，比如象今年早些时候爆发的sars病毒。 |
