Sheep foetal lung cells can be passaged for forty times, and each subculture can be used to isolate virus, so it is a very practical method of isolating OPPV.

• 绵羊胎肺细胞可传到40多代，且每一代次的细胞都可用于病毒的分离，因此这是一种非常实用的分离OPPV的方法。