But the mutations alone still didn 't make the virus transmissible between ferrets through respiratory droplets .

但是，仅仅这2个突变，仍然不能使病毒通过呼吸道飞沫在雪貂之间传播。

All donors are screened for known transmissible diseases .

所有捐献者进行己知传染性疾病的筛选。

But what mutations would make the virus more easily transmissible ?

但是何种变异才会使得这种病毒更易传染呢？

Only the additive genetic variance is transmissible by seed .

仅仅加性遗传方差是由种子遗传的。

Several circulating h5n1 avian influenza strains already have two of the mutations known to make experimental strains of the virus transmissible between mammals via respiratory droplets .

几个正在流行的h5n1禽流感病毒株，已知有2个突变，使病毒的实验毒株能通过呼吸道飞沫在哺乳动物之间传播。