How does a virus cause disease?
(Lansing State Journal, July 19, 1998)
In fact, this is how a virus causes disease. Viruses are known for causing diseases such as the common cold, flu and AIDS. A virus can't reproduce on its own because it doesn't have the chemical machinery to replicate its DNA, which is used to make new viruses.
Eventually, there are so many viruses in the cell that it bursts and the viruses are free to move on to other cells in the host and the process is repeated. As you can imagine, this can be very harmful to the host organism. For a one celled organism, this can be detrimental. For a multicellular organism such as ourselves, it can make us fell sick, and possibly, eventually kill us.
No cure has been found for a virus yet because they mutate so frequently that they can easily become resistant to antibiotics.