CRISPR is so familiar to you, it is the name of the most recent breakthrough gene editing technique.
The United States or any other country does not stand outside the current antibiotic resistance crisis. And when it comes to infection and antibiotic resistance in hospitals, Clostridium difficile in the US is a terrifying bacterium.
Each year C. difficile infects about half a million patients in the United States and kills 15,000 of them. This species of bacteria heads a list of dangerous bacteria, announced by the US Centers for Disease Control and Prevention (CDC).
However, recently in a University of Wisconsin-Madison study, scientists have found a way to counteract this bacterium without the need for conventional broad-spectrum antibiotics. This time, what they used was the “CRISPR pills” that caused confusion. They cause the bacteria to “commit suicide”.
In case you find CRISPR too familiar, it is the name of the breakthrough gene editing technique. Technology that we still worry about will create babies, designed arbitrarily according to parents’ wishes.
As we know before, CRISPR is a powerful but cheap gene editing technology. With the ability to correct human genes, this technology is being developed for many medical applications, from treating genetic diseases to cancer.
But because CRISPR is a very powerful and flexible tool, its scope of application is very wide. Associate Professor, Dr. Jan-Peter Van Pijkeren from the University of Wisconsin-Madison said:
He and his colleagues are also using CRISPR, developing it into a precise targeted infection treatment. This gene editing tool will give people the unique ability to “kill bacteria in a selective way.”
Back to the fact that the CRISPR method is named after a repeat of the DNA, humans first discovered it from the bacteria itself. The system of CRISPR repeats in bacteria is an immune defense mechanism, which is used to fight bacteriophages (viruses that infect bacteria).
The immune mechanism of bacteria is that they store the DNA of the bacteriophages entering the genome, on CRISPR fragments. The bacteria then uses these DNA to identify the invading virus. Just by identifying it, it will immediately use the Cas9 enzyme as a scissors, cutting off foreign genes from the virus to protect itself.
Now, Dr. Van Pijkeren’s idea is very simple: How to deceive bacteria, using the CRISPR system itself to cut back on their DNA?
To do that, Dr. Van Pijkeren’s lab is developing bacteriophages capable of carrying a custom CRISPR signal. They are infected with a harmless bacterium or the gut bacteria, before being compressed into a pill.
The reason because if not, the bacteriophages will be torn off by stomach acid. And if you want to cure the disease for humans, they must at least exist until reaching the goal of infection.
Dr. Van Pijkeren compared the bacteria that carry bacteriophages like mother ships. When the bacteria carrying the virus containing the CRISPR signal go through the stomach, it will enter the intestine.
At this time, the “mother ship” will release bacteriophages that infect any nearby C. difficile species. Because CRISPR signals have been customized to resemble bacterial DNA, they are easily tricked into cutting into their own DNA.
Dr. Van Pijkeren said, a difficult point in this study is the mechanism of wrapping bacteriophages on beneficial mother ships. It is still in the development stage and has not yet reached the test of animals.
As for the part of bacteriophages, previous researchers have shown that they are able to activate CRISPR to kill bacteria on the skin. This mechanism of deceiving bacteria has also been shown to help fight Shigella sonnei, which causes diarrhea in developing countries.
Some companies, including Eligo Bioscience and Locus Biosciences, have begun pursuing projects to commercialize antibiotic-based CRISPR.
The appeal of antibiotics using CRISPR are such drugs, theoretically, giving us very good targeting capabilities. It will selectively kill bacteria, only killing the pathogen that CRISPR has been programmed for, while preserving other microorganisms, such as intestinal bacteria.
Contrary to the wide spectrum of antibiotics currently in use, in order to kill pathogens, we must accept sacrifices, killing both bad bacteria and good bacteria. In fact, the overuse and abuse of broad-spectrum antibiotics is often the first cause of and promoting antibiotic resistance.
Herbert DuPont, director of the Center for Infectious Diseases at the University of Texas, said: “Whenever we pair patients in a hospital or nursing home, we provide them with antibiotics. facing the problem from C. difficile ”.
That’s why Dr. Van Pijkeren’s research becomes so necessary. The CRISPR method he developed may play a big role in the fight against antibiotic resistant bacteria in the future.
However, some other scientists say that Dr. Van Pijkeren’s team will have much work to do. Peter Fineran, a microbiologist at the University of Otago, New Zealand, said “there is still a way forward, until this method replaces our current antibiotics.”
Besides, he said that the advantage of CRISPR antibiotic is also its disadvantage. How to kill a variety of pathogenic bacteria at the same time, when each CRISPR antibiotic only infects and kills a specific bacterium?
According to Fineran, CRISPR antibiotics will still play a big role, but we will still have to develop other tools to fight bacteria. The CRISPR will temporarily be “an additional tool in the arsenal, countering the rise of today’s antibiotic-resistant bacteria.”