Fighting Superbugs With Their Own Genes

From the WebMD Archives

A dramatic discovery in gene-editing may give us a powerful tool to fight disease.

It’s called CRISPR, and it’s got researchers jumping for joy.

“It’s totally revolutionized biology… and we’re only at the beginning,” says James Dahlman, a chemical and bioengineer at the Georgia Institute of Technology.

This discovery that could change the world came about when one of science’s worst fears was realized.

The Lightning Bug

People have worried about it for years: a superbug fueled by bacteria that can withstand the most powerful antibiotics.

And now it’s here -- in the U.S.

In April, a 49-year-old woman went to a clinic in Pennsylvania with symptoms of a urinary tract infection. Researchers soon learned she had a gene that made her infection resistant to all antibiotics.

“The medicine cabinet is empty for some patients,” CDC Director Thomas Frieden told the National Press Club after the discovery. “It is the end of the road for antibiotics unless we act urgently.”

Fortunately for all of us, scientists are acting urgently. The results are promising.

The Need for Solutions

The CRISPR revolution started on the smallest of scales. It comes from bacteria. And maybe it has come in the nick of time.

Antibiotics and drugs like them have been used for more than 70 years. They’ve saved the lives of millions. But often, they’re over-prescribed. As a result, we’ve seen the rise of resistant bacteria that no longer give in to the drugs that once did the job.

“This is creating a huge challenge for our medical system,” says MIT’s Timothy Lu, MD, PhD, one of the leading researchers in the world of CRISPR.

Antibiotics work on bacterial infections.  They don’t work on viruses, but, Lu says, some doctors will give you an antibiotic even if it’s not designed to cure what you have.

“Another challenge with antibiotics is that they kill both good and bad bacteria,” Lu says.

So, drug choices for a lot of bacterial infections are becoming limited. In the case of the superbug, there are no known drug choices.

As if things weren’t already dicey, each year, drug-resistant bacteria cause about 23,000 deaths.

But as infections have grown stronger, so have the tools of science.

Continued

A Major Discovery

Researchers discovered CRISPR molecules in nature. It’s something microbes have used to defend themselves from viruses for millions of years.

They’re made up of repeating genetic sequences. These patterns are interrupted by things called “spacers.” They’re leftovers of genetic code from past invaders (like a virus). So, the CRISPR system is like a genetic memory bank that helps the body find and destroy invaders, when and if they return.

Over the past several years, scientists have figured out how to engineer CRISPR to edit the genetic makeup of human cells. Today, you may hear about something called the CRISPR-Cas9 system. Cas9 is a chemical your body makes that acts like a pair of scissors, cutting away offending DNA.

So basically, CRISPR-Cas9 is a precision tool that can be used to target specific stretches of genetic code, editing DNA -- cutting and pasting, if you will.

In the 3 years since scientists at the University of California-Berkeley, Harvard, and M.I.T. demonstrated the CRISPR gene-editing tool, hundreds of experiments using it have followed. Some of the results, like those from the labs of Dahlman and Lu, may herald a new age in medicine.

Dahlman’s lab is working on genetic drugs that can target complicated combinations of genes simultaneously. And Lu’s lab has used CRISPR to selectively kill bacteria that has genes prone to antibiotic resistance, or to cause disease.

Right now, that’s Lu’s life’s work.

“Since I was a PhD student, my goal has been to develop new, alternative sources of therapeutics to fight against disease,” he says.

And that could change which medicines doctors give you and when.

What Happens Now?

Because of CRISPR (short for "clustered regularly interspaced short palindromic repeats", by the way), researchers foresee a time when devastating genetic conditions will be effectively treated, and when many diseases will be eliminated.

Among the ones CRISPR is expected to help are:

  • Hemophilia
  • Sickle cell anemia
  • HIV

We’re definitely not there yet, but the path seems clear.

“We’re already doing studies that we could only dream about just 4 years ago,” Dahlman says.

And one of the best parts about it is that the technology doesn’t exactly break the bank for the labs that are doing the research.

“This incredibly powerful tool allows you to do gene editing at a cost and scale that is unprecedented,” Lu says.

So, the clamor over CRISPR in the scientific community has reached crescendo levels, and for good reason. This is world-changing technology.

“This is really about the democratization of science,” Lu says.

WebMD Feature Reviewed by Laura J. Martin, MD on June 8, 2016

Sources

SOURCES:

James Dahlman, assistant professor of biomedical engineering, Georgia Tech.

Timothy Lu, MD, PhD, Associate Professor of Biological Engineering and Electrical Engineering and Computer Science, M.I.T.

Medscape: “First U.S. Case of E coli Resistant to Last-Resort Antibiotic.”

Journal of American Society of Microbiology.

Centers for Disease Control and Prevention.

Quanta Magazine" “Breakthrough DNA Editor Born of Bacteria.”

Chemistry World: “The Cutting Edge of Gene Editing.”

Centers for Disease Control and Prevention (page/article on Drug Resistance).

McGovern Institute/M.I.T.  

Broad Institute/Harvard and M.I.T.

Carlos Slim Health Institute (Health Updates article).

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