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July 09, 2007

Synthetic biology uses viruses to fight biofilms

Synthetic biology used to make viruses to combat harmful 'biofilms'


This diagram shows how an engineered virus,T7, destroys a biofilm composed of E. coli bacteria. Graphic courtesy / Timothy Lu and James Collins

In one of the first potential applications of synthetic biology, an emerging field that aims to design and build useful biomolecular systems, researchers from MIT and Boston University are engineering viruses to attack and destroy the surface "biofilms" that harbor harmful bacteria in the body and on industrial and medical devices.

They have already successfully demonstrated one such virus, and thanks to a "plug and play" library of "parts" believe that many more could be custom-designed to target different species or strains of bacteria.

The work, reported in the July 3 Proceedings of the National Academy of Sciences, helps vault synthetic biology from an abstract science to one that has proven practical applications. "Our results show we can do simple things with synthetic biology that have potentially useful results," says first author Timothy Lu, a doctoral student in the Harvard-MIT Division of Health Sciences and Technology.

They found that their engineered phage eliminated 99.997% of the bacterial biofilm cells, an improvement by two orders of magnitude over the phage's nonengineered cousin.

"We hope in a few years, it will be easy to create libraries of phage that we know have a good chance of working a priori because we know so much about their inner-workings," says Lu.

Synthetic biology also makes it possible to control the timing of when a gene is expressed in an organism. For instance, Lu inserted the DspB genes into a precise location in the T7 genome so that the phage would strongly express it during infection rather than before or after.

Though phages are not approved for use in humans in the United States, recently the FDA approved a phage cocktail to treat Listeria monocytogenes on lunchmeat. This makes certain applications, such as cleaning products that include phages to clear slime in food processing plants, more immediately promising. Another potential application: phage-containing drugs for use in livestock in exchange for or in combination with antibiotics.

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