When two viral strains infect the same cell, their gene segments can reassort just like figures on a slot machine, forming new combinations and thus novel versions of the virus.

• 当两种品系的病毒感染同一个细胞时，其中所带各段基因，就会像吃角子老虎上头的数字一样，重新配对而形成新的组合，也就是新品系的病毒。