it would cause no damage because it could not reproduce.

因其不能繁殖所以不会对身体造成伤害
It's reproduction of the virus and passage of that virus onto new cells

病毒一旦繁殖并进入新细胞
which causes the problems with disease that we associate.

就会带来相关病症的危害
They often kill the cells that they infect,

它们经常杀死被感染的细胞
and that's a problem with viruses.

这是病毒的一大危害
A virus isn't troublesome until it infects a host cell and

病毒在感染宿主细胞后变得很棘手
when it infects a host cell it becomes troublesome

当其感染细胞后棘手的是
because it takes over some of the host machinery

因为病毒能够接管宿主的复制机能
for DNA synthesis,

合成自身DNA
transcription, and translation and starts making more viruses

转录翻译来制造更多病毒
and this happens largely in the cytoplasm of the cell.

这往往发生在细胞质中
How is your immune system going to recognize

你的免疫系统怎样才能识别