Bacteria are everywhere. They live in the soil and water, on our skin and in our bodies. Some are pathogenic, meaning they cause disease or infection. To design effective treatments against pathogens, researchers need to know which specific genes are to blame for pathogenicity.
Scientists can identify pathogenic genes through genetic engineering. This involves adding human-made DNA into a bacterial cell. However, the problem is that bacteria have evolved complex defense systems to protect against foreign intruders—especially foreign DNA. Current genetic engineering approaches often disguise the human-made DNA as bacterial DNA to thwart these defenses, but the process requires highly specific modifications and is expensive and time-consuming.
In a paper published recently in the Proceedings of the National Academy of Sciences journal, Dr. Christopher Johnston and his colleagues at the Forsyth Institute describe a new technique to genetically engineer bacteria by making human-made DNA invisible to a bacterium’s defenses. In theory, the method can be applied to almost any type of bacteria.
Johnston is a researcher in the Vaccine and Infectious Disease Division at the Fred Hutchinson Cancer Research Center and lead author of the paper. He said that when a bacterial cell detects it has been penetrated by foreign DNA, it quickly destroys the trespasser. Bacteria live under constant threat of attack by a virus, so they have developed incredibly effective defenses against those threats.
The problem, Johnston explained, is that when scientists want to place human-made DNA into bacteria, they confront the exact same defense systems that protect bacteria against a virus.
