Viruses can exist either extracellularly or intracellularly.

病于细胞外，也于细胞内。

They can exist either extracellularly where the virus is inactive and isn't capable of reproducing or intracellularly where the capsid is removed and the virus becomes active.

它们于细胞外，处于不活跃状态，无法复制，或者细胞内，脱掉衣壳，变得活跃。