Question

what is virus hoe do they multiplay

Answer 1

Virus is an infective agent that is too small to be seen and is able to multiply only within the living cells of a host.

The virus injects its genetic material into the host cell and the host cell uses the genetic material to make new viruses.

Answer 2

For viruses to multiply, they usually need support of the cells they infect. Only in their host´s nucleus can they find the machines, proteins, and building blocks with which they can copy their genetic material before infecting other cells. But not all viruses find their way into the cell nucleus.