Nature defences against viral infections

1.      Interferons - In 1957 Issue and Lindenmann discovered that vertebrate cells infected with viruses, produce a diffusible antiviral protein which they named interferon. Later interferon's were found to be a class ofglyco0proteins.Interferon diffuses put from an infected cell, enters into similar cells enters into similar cells in the neighbourhood .and imparts a defense   mechanism to these cells against viral infection. It has no action upon proteins in the infected cells. it is therefore used for therapeutic and  preventive purposes in viral infections

2.      Body immunity -Viruses are effectively poisonous these are good antigens to induce active production of specific antibodies and immune reaction in the body .Thus viral infection  establish prolonged and effective immunity in the body against reinfection by the respective viruses.

Immunoprophylaxis - Vaccines

Vaccines have been extensively used to build a strong and prolonged anti viral immunity in the body against possible viral infections. The vaccines contain inactivated virions themselves which cannot cause the concerned diseases, but still act as antigens to induce antibody production by the immune system of body.

Chemotherapy- Antiviral drugs

Since viruses are strictly  intracellular parasites  chemotherapeutic agents and antibiotics which help in the treatment and control   of bacterial diseases are ineffective for viral diseases. Central antiviral drugs have however been prepared since 1960.Some   important antiviral drugs are Thsosemicarbazone  for treatment and prevention of smallpox Ribavirin for influenza Deoxyuridines for herpes foscarnet for  hepatitis B,etc.