Dangers of Phage Therapy

I was in the car the other day talking to my brother about the days phage lab, I had just explained the concept of phage therapy to him when he raised a very good point. He likened using phage to kill bacteria in our body to early settlers attempting to introduce carnivores such as cats, stoats and wesales to kill pests like rabbits, mice and rats. I was quite impressed to be honest as he has no biological background what so ever, but it really made me think. The idea is simple enough, when settlers came to New Zealand they brought with them rabbits and other pests. the numbers of these pests got out of hand and when conventional methods of killing them such as trapping and poisoning became ineffective they brought carnivores over that would kill the pests, seems logical. phage therapy works in essentially the same way, antibiotics are becoming less and less effective so why don’t we use a virus that will kill bacteria for us? But what if my brother is right? What if this new and wonderful idea results in ruin? So i did some exploring to see what i could find on the matter.

Phage therapy will attempt to use highly specific bacteria phages to kill off bacterial infections in our body, and so far it seems like a valid idea. Although there is still a lot that is unknown about phage and their relationship with bacteria there have been numerous animal trials of the proposed therapeutic treatment of bacterial infections with phage and even a couple of hundred human trials in western Europe from 1920 onward. Both the animal and human trials showed the treatment to have an effect quite rapidly (24-48h) and yet people still have reservations about their continued use. The most common objection is that the phage will somehow change and begin to attack human cells. From the literature I have been reading this should not be possible, phage attach themselves to bacteria that have a very specific combination of different molecules such as proteins, carbohydrates and lipids. This coupling is so specific often different strains of the same bacteria are not effected by the same phage.  for this reason the likely hood of a bacteria phage infecting a human cell is very very low. If that is not enough to reassure you there are already bacteria/phage relationships occurring in humans animals and the environment and have been for thousands of years.

Some really usefull sites used in this blog are listed below.

http://www.cienciaviva.eu/rede/oceanos/2desafio/visaogeral.pdf

file:///C:/Users/Nathan%20Long/Downloads/32.pdf

http://aac.asm.org/content/45/3/649.short

 

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2 Responses to Dangers of Phage Therapy

  1. charlotterobertson007 says:

    I just had a brain-wave. It isn’t necessarily the danger of the phage evolving and gaining the ability to infect humans that we should be worried about. It is the bacteria themselves. What happens if our theraputic phage causes a pathogenic bacteria to become more dangerous or deadly? We already know that phage can integrate their genomes into bacterial genomes forming prophage (phage genome in bacterial genome) and lysogens (bacteria with a prophage). This automatically provides the lysogen with immunity to infection by the same type of phage. What if this integration changed bacteria in a way that made them more resistant to phage or antibiotics? But as you have pointed out, bacteria and phage have been living in the same environments for many, many years so I guess it isn’t so likely that we could induce this kind of change in bacteria in such a relatively small timeframe?

  2. naturaljess says:

    Your brother made a good correlation there. This can also be likened however to European settlers giving smallpox diseased blankets to the Native Americans. As Charlotte has mentioned above, this common use of using phages to kill the bacteria that cause disease could lead to bacteria mutation, and due to natural selection could breed more deadly bacteria, who are both antibiotic and phage resistant.

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