Stories about: Min Dong

Botulism toxin X: Time to update the textbooks, thanks to genomic sequencing

botulinum toxin X
Botulinum toxin X is the first new botulinum toxin to be identified since 1969. (Jason Wilson/Flickr)

Botulism is a rare, potentially fatal paralyzing illness. It’s the reason we shouldn’t feed infants honey and why we need to take care in consuming home-canned foods: they can potentially contain nerve-damaging toxins produced by Clostridium botulinum. Botulinum toxin is classified as one of the six most dangerous potential bioterrorism agents.

There are seven known types of botulinum toxin. Toxins A and B were first identified in 1919, and first purified in 1946 and 1947, respectively. (Both are also used medically.) Toxins C, D, E and F eventually followed. The last, toxin G, was identified in 1969 in soil bacteria in Argentina.

And that’s where it’s stood until now. But to truly defend against botulism, we need to know all the toxins made by the various C. botulinum strains, since each requires a separate antibody to neutralize it.

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Mutated botulinum neurotoxin B: A stronger player in the Botox world?

Clostridium botulinum

Famously associated with smoothing out wrinkles, botulinum toxin — better known as Botox — has been in use for 40 years now. Initially approved as a treatment for crossed eyes and then facial wrinkles, its on- and off-label uses today extend to urinary incontinence, migraines, perspiration, spasticity and even depression. But the diffusion of the toxin away from the injection site can also cause side effects like difficulty swallowing and drooping of the face.

Now, scientists have created an altered botulinum toxin, one that works much better than its natural version and with potentially fewer side effects. Their findings are written up in Nature Communications.

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Entry door for deadly C. difficile toxin suggests new mode of protection

Clostridium difficile
C. difficile (Wikimedia Commons)

Clostridium difficile, also called “C. diff,” tops the CDC’s list of urgent drug-resistant threats. Marked by severe diarrhea and intestinal inflammation, C. diff has become a leading cause of death from gastrointestinal illness, causing half a million infections a year in the U.S. alone.

C. diff flourishes best in hospitals and long-term care facilities where people are on long-term antibiotic treatment. “Antibiotics clear out the normal intestinal bacteria and create a space for C. diff to colonize and grow in the colon,” says Min Dong, PhD, who researches bacterial toxins in the Department of Urology at Boston Children’s Hospital.

In today’s Nature, Dong and postdoctoral fellow Liang Tao, PhD, together with researchers at University of Massachusetts Medical School, reveal how C. diff’s most potent toxin gets into cells. The toxin’s entryway, a receptor called Frizzled, provides an important and interesting clue to fighting the hard-to-eradicate infection.

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