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Sunday, January 2, 2011

What rhymes with beige? Why, bacteriophage of course!

Bacteriophages are small viruses that infect bacteria and kill them by multiplying and essentially filling the bacterial cell to bursting.  Here is a small animation of the life cycle of one bacteriophage.  The word lytic means that the cell is destroyed by the process.  After the phages reproduce inside the bacteria cell, they burst out and the cell is demolished.  Adsorption is the gathering together of the phage on the surface of the cell.

The bacteriophage has attachment sites on it that correspond with receptor sites on the bacteria.  In other words, they don't attack just any cell, only specific cells.  So a bacteriophage that is meant to destroy e. coli (these are called T4 bacteriophage) will only attach to an e. coli cell and then multiply, destroying the e. coli cell.

These viruses are much smaller than the bacteria that they destroy. Each time a phage invades a bacteria cell, it produces between 50 and 200 new phage viruses within the bacteria cell.  Once the host bacteria are destroyed and are no longer present, the phages die off, too.

Phages are found all over the planet.  Anywhere that bacteria live and thrive phages will be found.  They are especially abundant in water.

Phages have been known since ancient times.  There have been documented reports of river waters having the ability to cure infectious diseases, such as leprosy. In 1896, Ernest Hanbury Hankin reported that something in the waters of the Ganges and Yamuna rivers in India had marked antibacterial action against cholera and could pass through a very fine porcelain filter.

They have been used for over 60 years as an alternative to antibiotics in the former Soviet Union and Eastern Europe.  They are seen as a possible therapy against multi-drug resistant strains of many bacteria. 

Phages were discovered to be anti-bacterial agents but the medical trials performed in western countries in the early 1900's were poorly conducted and the scientists really didn't understand what a phage was.  Many of the trials were conducted on totally unrelated diseases such as allergies or viral infections.  So phage therapy was ruled as untrustworthy.  Soon antibiotics were discovered and widely used.  They are popular because they can treat a wide range of diseases and are easy to manufacture and then store. 

Development of phage therapy was largely abandoned in the West, but continued throughout the 1940s in the former Soviet Union. It was used for treating bacterial infections throughout the country, including the soldiers in the Red Army.  The literature was published in Russian or Georgian and so it was not available for many years in the United States.  It is still used in the country of Georgia and other Eastern European countries.

In August, 2006 the United States FDA approved using bacteriophages on cheese to kill the Listeria monocytogenes bacteria.  In July 2007, the same bacteriophages were approved for use on all food products.

Government agencies in the West have for several years been looking to Georgia and the Former Soviet Union for help with exploiting phages for counteracting bioweapons and toxins, such as anthrax and botulism.  There are many developments with this among research groups in the US.

There seem to be many advantages of developing bacteriophages for use in many fields, including clinically.  But there are a few downsides, also.  One is getting the phage to the bacteria.  If used orally, some might not pass the stomach acid without being destroyed.  If used as a cream or as an injection, it still needs to get to where it is going without the body's immune system seeing it as a foreign threat.

A more non-scientific downside to the use of phage therapy is that due to intellectual property laws and the fact that currently its use is public, so the technique of phage therapy would not be patentable. The development of drugs is very expensive and larger pharmaceutical companies have no motivation to go through the complicated and costly process if there is no patent protection on the products they may create.

Now you have heard something interesting.

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