According to Dr. Chase Beisel, an assistant
professor of chemical and biomolecular engineering at North Carolina State
University,Conventional antibiotic treatments kill not only ‘bad’ but ‘good’ bacteria
as well, leading to accidental consequences, such as opportunistic infections. Researchers
from North Carolina State University have developed a de facto antibiotic "smart
bomb" that can recognize specific strains of bacteria and disintegrate
their DNA, eliminating the infection. This technique offers a potential
approach to treat infections by multi-drug resistant bacteria. By the means of
this technique, it is possible to clear specific bacteria strains selectively
without affecting good bacteria populations.
Many bacteria have a specific part of immune system termed as
CRISPR-Cas system, which protects bacteria from invaders such as viruses by
creating small strands of RNA called CRISPR RNAs. These RNAs match DNA
sequences specific to the invader. As soon as these RNAs find match DNA, they
allow action of a particular protein called Cas protein that cleaves DNA. The
NC State researchers have used this concept to cause bacterial suicide by designing
CRISPR RNAs to target DNA sequences in the bacteria themselves. Bacterium's
CRISPR-Cas system attacks its own DNA, hence, cleaving it.
Beisel claims that this approach not just specifically eliminates
targeted bacteria, but is easy and has high potency. The researchers tested the
approach in controlled cultures with different combinations of bacteria
present, and were able to eliminate only the targeted strain. "For
example, we were able to eliminate Salmonella in
a culture without affecting good bacteria normally found in the digestive
tract," Beisel says.
Further, researchers also managed to demonstrate the accuracy of
the technique by eliminating one strain of a species, but not another strain of
the same species which shares 99 percent of the same DNA.
Through CRISPR-Cas system approach, the mechanism of antibiotic
resistance was also by-passed.
The researchers are currently working to further develop
effective methods for delivering the CRISPR RNAs in clinical settings and also
developing antibiotics using programmable CRISPR-Cas systems.
