sentence: Antibiotics have no effect on viruses, but several antiviral drugs have been developed.
sentences_before: Viral infections in animals provoke an immune response that usually eliminates the infecting virus. Immune responses can also be produced by vaccines, which confer an artificially acquired immunity to the specific viral infection. However, some viruses including those causing AIDS and viral hepatitis evade these immune responses and result in chronic infections.
concept_name: antibiotic
headings: Virus
categories: Viruses