Methods: Parainfluenza virues with different hemagglutination(HA) titer were used to infect MDCK cells to observe their growth condition and exam the change of HA titer.

• 方法:用不同血凝效价副流感病毒感染MDCK细胞,观察副流感病毒在细胞上的生长情况,并检测血凝效价的变化。