The researchers identified three genes they believed were important for the bird flu (formally known as avian influenza) virus to reproduce in the chickens.

研究人员确定了三个他们认为对禽流感病毒在鸡体内繁殖很重要的基因。

They took the HA gene from avian influenza viruses found in Vietnam and made millions of mutant versions, each of which was spliced back into a copy of the original virus.

他们提取出于越南发现的禽流感病毒中的血凝素基因，然后将其改造生成了数百万种突变类型，接着将每一种突变类型与复制的原始病毒相接合。