Viruses can only replicate with in a cell or living tissue applies to a viral infection.
Viral infections are infections that are caused by viruses. Viruses are microscopic organisms that contains a core of genetic material (DNA or RNA) enclosed by a protein coat. Viruses are not made of cells and they are very tiny and smaller than bacteria. Viruses require a living cell (host organism) to replicate and produce other viruses similar to them. Viral infections cannot be treated with antibiotics, antiviral medicines are used instead. Examples of viral infections include; common cold, flu, smallpox, HIV/AIDS and Ebola.