Viruses only contain a shell of protein and some DNA and RNA genetic makeup materials.To reproduce, the virus invades a cell in a host and uses the cell to produce more of itself.

• 病毒只有一个蛋白质外壳和一些DNA和RNA这样的遗传物质，通过侵入宿主细胞并利用宿主细胞来进行复制。