Antibiotics are basically poisons that only affect bacteria. Bacteria are cells, just like every other living thing, but they are very, very different from multicellular organisms. Their biochemistry and molecular biology are so different that some things which are toxic to bacteria are utterly harmless to you and me, and vice versa.
But viruses, well…
You can’t poison a virus because a virus is not alive. A virus has no metabolism. A virus does not take in nutrients, because it isn’t a living thing. It’s just a bit of genetic code wrapped up in a protein shell.