Are any naturally-occurring beneficial viruses?

29 January 2012

Question

Dear Chris,

I'm wondering if there are any naturally-occurring beneficial viruses, and in particular, in the human body?

Thank you so much for the best podcasts on the web!

My very best wishes,

Kathlyn Powell

Answer

I reckon the answer is yes. First and foremost, I think if you think about viruses that prey on bacteria because just like us, bacteria can catch a cold too. Bacteriophages will attack bacteria and kill them and this has actually been used as a form of antibiotic therapy and it was pioneered in Russia, but it has actually been used all over the world. What scientists do is find these viruses that discreetly and specifically prey on certain strains of bacteria and specifically the bacteria that's causing an infection in a patient. They can grow up those particular bacteriophages, they put them into the patient, they are unable to infect a person's cells because they lack the right docking system to latch onto one of our cells. They go into the bacteria, grow in the bacteria, each infected bacterium makes hundreds of new bacteriophages which then kill hundreds more bacteria, until it runs out of bacteria to kill, and then the whole thing just disappears. So I'd say those are pretty beneficial viruses. There are also some viruses which infect us which actually we think may, despite the fact we're getting infected by them have a beneficial effect on our health. There was a paper published in Nature in 2007 and it's by a guy called Skip Virgin in the States and they demonstrated that if they got mice and infect them with the rodent equivalent of glandular fever, which is a Herpes virus, or Cytomegalovirus, another Herpes virus, and then after the animals had cleared the infection, they challenge them with listeria or with bubonic plague, the mice were all fine. They all survived. If they challenged mice that haven't had those herpes infections first then they all died. And their theory is that because these viruses get into the body and they then establish a life-long infection what's called a 'latent infection' they in some way reprogramme the immune system and it's almost like the immune system is using the virus because it's got a very big genetic code in the virus, almost like a USB pen drive for priming the immune system in a way that it's forgotten how to do itself. So, I would argue that's probably one kind of beneficial virus too, but a very nice question.

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