Many people use antibiotics, making bacteria more resistant to antibiotics. Scientists see CRISPR as a possible alternative to battle with pathogenic bacteria.
CRISPR is a method to cut and paste DNA. It seems an excellent method to repair and remove certain mutations. On the other hand, there are concerns because little is known about the effects of the ‘cut and paste’ of DNA.
CRISPR is created by nature: bacteria use the method a long time to protect themselves against viruses. When a virus invades a bacterium, the bacterium incorporates the DNA of this virus in a particular DNA sequence which is called “Clustered Regularly interspaced Short Palindromic Repeats” (short: CRISPR) by researchers. Subsequently, the bacterium creates RNA that contains a copy of the DNA of the virus. This RNA is recognized by an enzyme which is referred to simply as Cas (CRISPR-associated proteins).These enzymes allow to guide themselves through RNA (also referred to as guide-RNA) to the virus. Once there, the enzyme cuts the DNA of the virus into pieces, stopping the virus to multiply.
Cut and Paste
It appears that enzymes can not only cut viral DNA into pieces but in fact, the DNA of any organism. In addition, an error portion can be replaced by a desirable gene DNA sequence. The piece of DNA is then – after cutting – paste in between. This offers much possibilities. The method is less than five years old, so researchers are still exploring all options.
In the new paper of the scientific journal Science researchers report that they want to use CRISPR to combat Clostridium difficile. This is a bacterium commonly found in the intestines. Normally, the bacterium does not cause problems, but in disturbance of the intestinal flora – for example, by use of antibiotics – can cause excessive growth. This may lead to an inflammation of the large intestine (Pseudomembranous colitis). According to the US Centers for Disease Control and Prevention 250,000 infections take place annually in the United States. The annual medical cost billion dollars. To date, approximately 14,000 Americans died from the consequences of this ‘hospital bacteria’.
Now it seems possible to defeat this bacterium. Researcher Jan-Peter van Pijkeren from the University of Wisconsin-Madison wants to use bacteriophages (= small viruses that only infect specific bacteria) to deliver the wrong message to C. difficile. The bacterium will cut into its own DNA, which he makes himself harmless. These bacteriophages normally would be destroyed rapidly by stomach acid. Therefore Van Pijkeren plans to stop the phages in a pill, along with a brigade harmless bacteria. These probiotics protect the phages while traveling through the body. Only in the gut the phage attack and hack the C. difficile bacteria.
Bacterial Mass Murder
Pijkeren claims that researchers are still in the early stages. It has not even been tested on animals. It may therefore take some time before this pill can replace antibiotics. Yet there is hope, because researchers have previously shown that bacteriophages by CRISPR can destroy skin bacteria. In addition, several pharmaceutical companies have begun examining CRISPR antibiotics as an alternative to regular antibiotics. Regular antibiotics kill many bad, but also many good bacteria. Thanks to these bacterial CRISPR massacre is no longer needed.