The first is a “reassortment” event, in which genetic material is exchanged between human and avian viruses during co-infection of a human or pig.

第一是“重组”，在人或猪合并感染人类或禽类病毒时发生基因材料交换。

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Avian influenza viruses become more active when temperatures turn cooler.

禽流感病毒在气温转为凉爽时变得更为活跃。

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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。

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Avian flu viruses can sometimes spread to domestic poultry and cause large-scale outbreaks of serious disease.

FORBES: Bird Flu Claims More Lives In Shanghai

The World Health Organization says that most avian flu viruses do not infect humans and the majority of H5N1 cases have been associated with contact with infected poultry.

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His group will attempt to nail down exactly how many mutations - and which - are sufficient to make the H5N1 avian flu virus airborne, and whether these particular mutations can also make other bird flu viruses airborne.

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