Bacteriophages are viruses that invade Bacteria and reproduce there, usually killing the bacteria. Researchers are looking for bacteriophages that will kill bacteria but leave human cells alone. The HIV virus infecting humans can produce over a million different mutants each 24 hours, and so some will overcome the hosts immune systems and also produce drug resistant HIV strains. These resistant strains will then rapidly reproduce in the host. The viral coat of protein differs from the bacterial cell wall.
Antibiotics attack the bacterial cell wall and stop bacteria from growing and reproducing.
Some doctors give antibiotics to counteract any combined viral and bacterial infection. There are relatively few anti-viral drugs. Acycolvir inhibits viral DNA synthesis. Some of them have later returned to the cell's DNA and are incorporated into the hosts chromosomes, awaiting a signal before getting switched on to reproduce.