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CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats, and is a new system that is revolutionizing how we approach science.

What’s the big deal about CRISPR?

Jarrod Johnson

Posted on Jan 15th, 2018

Several centuries ago, inventions such as the compound microscope and the telescope changed the way we could see the world around us, opening our eyes to both the smallest forms of life and the larger cosmos in which we live. In the past few years, a new technology has emerged that is transforming our understanding in a similar way. It’s called the CRISPR/Cas system and it is redefining the landscape of possibilities for basic biology research, agriculture, and medicine.

Our understanding of the biological world is limited by the tools we have at our fingertips. Rarely do new technologies alter our perceptions of the world around us as much as the microscope or the telescope. It remains to be seen what the full impact of CRISPR/Cas will have, but what is clear is that not only is CRISPR/Cas changing the ways in which scientists can look at our world, it is an instrument that can change life as we know it in our world.

So what exactly is CRISPR/Cas?

Essentially, the CRISPR/Cas system is a revolutionary gene editing technology that makes it possible to precisely modify sequences of nucleic acids (DNA and RNA), which are the building blocks of life. Because of its simplicity and efficiency, it has been adopted by researchers all over the globe to answer basic questions in biology, like “What is the function of gene X?” and it has opened the door for new therapies and breakthroughs in medicine.

Now, scientists and clinicians have the tools to ask, “Can we edit our DNA to prevent disease and fix genetic disorders?”

The discovery of a new tool

Imagine for a moment, that you don’t know what scissors are or what they do. If you were out for a walk one day and found a pair of scissors lying on the ground next to a piece of string, you might stop and take a look if they happen to catch your attention. If you were curious, you might pick them up and examine those scissors a little closer. With a little tinkering, ingenuity, or tomfoolery, you might even discover that those sharp blades could cut the piece of string rather easily.

That’s essentially how the discovery of the CRISPR/Cas system played out. It began in Japan in 1987, with a team of scientists studying the genomes of bacteria. They found interesting genomic regions that contained repeating sequences of DNA. In between these regions, the DNA looked particularly strange because it did not match with any known prokaryotic DNA sequences. It wasn’t until 2002 that a similar pattern was found in single-celled microorganisms called archaea by a team in Spain. Soon after, it was discovered that these strange DNA sequences in bacteria matched DNA sequences in bacteriophages that were known to infect them (Yes, bacteria can get infected, too!).

Researchers hypothesized that these repeating sequences of DNA were part of an immune system. The term CRISPR is a snappy acronym for these sequences, known as Clustered Regularly Interspaced Short Palindromic Repeats. The sequences in between the repeats (the bits and pieces of foreign DNA) act as molecular “most wanted” posters, serving to target host nucleases -- guiding the scissors, if you will -- to cut up the genomes of any potential invaders.

Image Source: Biosciences for Farming in Africa

In 2007, a research team in France first demonstrated that CRISPR was a naturally occurring adaptive immune system. A few years later, in 2010, researchers in Canada identified the protein that did the cutting: a protein called Cas9 functioned as the molecular “scissors.” Not too long after that, several labs made key mechanistic discoveries that turned this naturally occurring system into an incredibly useful tool.

Scientists have discovered ways to guide the scissors in the laboratory, and are now capable of repurposing the naturally occurring CRISPR/Cas9 system to make genetic modifications in almost any piece of DNA, in practically any organism.

This has led to a fundamental revolution in the way basic science is performed. Researchers around the world are now able to adapt the CRISPR/Cas9 system (and related Cas family “scissors”) to knockout, activate, tag, or modify genes in single cells, plants, animals, and perhaps someday soon…humans.

What’s next for CRISPR?

It’s possible that the first clinical trials using CRISPR technology could begin in the US and Europe in 2018 for the treatment of beta thalassemia and sickle-cell disease, both of which are inherited blood disorders caused by mutations in single genes. If we fix the gene, we fix the disease.

Progress could be mired by a heated patent battle over who owns CRISPR technology rights. Additionally, researchers must carefully navigate the ethical implications of gene editing in humans, especially since the first evidence of CRISPR-modified human embryos was published earlier this year. Nevertheless, CRISPR-based treatments for many disorders are on the horizon.

But why stop with one gene? Using advanced computational tools, systems biology laboratories can generate CRISPR libraries that target every gene in the genome.

Researchers here at CID Research are using these genome-wide libraries to get insight into host-pathogen interactions. Using genome-wide screens and more targeted CRISPR approaches, we are learning about HIV, tuberculosis, malaria, and other pathogens at a quickening pace.

Just as the microscope and telescope have led to breakthroughs in scientific research, we now have CRISPR technology at our fingertips. Our mission is to fight infectious disease, and this transformative instrument is undoubtedly accelerating our progress.

The future looks very bright.

About the Author

Jarrod Johnson is a Senior Scientist in the Aderem lab at the Center for Infectious Disease Research. He is working to understand how innate immune cells detect and respond to pathogens such as HIV. Jarrod uses systems biology tools, genome-wide screens, and targeted genetic perturbations to study signaling networks in human dendritic cells. He earned his Ph.D from UNC - Chapel Hill where he worked under the mentorship of Jude Samulski at the Gene Therapy Center. As a postdoctoral fellow, Jarrod trained with Dan Littman at NYUs Skirball Institute for Biomolecular Medicine. Outside of the lab, Jarrod enjoys making memories with his two kids, eating massive breakfasts, exploring the outdoors, and playing jazz guitar.

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