Which condition is required for viruses to reproduce?

A host is required so that the virus is able to reproduce.

Explanation:

Unlike bacteria, viruses cannot survive without a host. They primarily survive while attaching itself onto a host's cell. So therefore, in order for meiosis to occur within a virus, it needs a host first. In addition, viruses don't need another virus because viruses are prokaryotic cells.

friedrich meischer discovered it in white blood cell