Are any viruses good for us?

16 September 2007

Question

Viruses - are they any good? Are any of them actually good for us or symbiotic? For example, cowpox provides immunity to smallpox.

Answer

This may be true, despite that fact that most people think of a virus as being something that makes them feel awful! A recent piece of research in Nature magazine, by US scientist Skip Virgin, suggests that being infected by one of the family of viruses known as Herpes viruses, such as herpes simplex, which causes cold sores, or Epstein-Barr virus, which causes glandular fever can help to boost the function of the immune system. When they infected mice with the rodent equivalents of either of these infections, the mice developed a much better immune response to other pathogens than mice which had never been infected. To prove this, they exposed the mice to the bacteria which causes plague and also listeria; they found these mice to be 100% protected against these bacteria compared with animals which had never been infected with a Herpes virus, which all died. When they studied these mice, they found signalling molecules called interferon gamma were being produced at a much higher level than normal, and this molecule is known to stimulate the immune system.

They think that, because we've been living with members of the herpes viruses for millions of years, the body has come to rely on infection to provide additional gene functions, or immune stimulating factors, which our body no longer has. This programmes a more powerful the immune system, and we get benefit. It's almost a symbiosis, we give the virus a home and it gives us a better immune system...

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