Enterotoxigenic E. coli and Shigella cause hundreds of millions of stomach‑flu cases each year. They are a top reason for deadly diarrhea, especially in children. So far, no vaccine works well against either germ.
Researchers at Washington University School of Medicine in St. Louis found a common weakness in these bugs. The same three enzymes let the bacteria cut through the gut’s protective mucus layer and start an infection.
When the scientists gave patients and volunteers antibodies that target a shared part of these enzymes, the antibodies stopped all three germs from breaking the mucus barrier. This means a single vaccine could protect against several major diarrhea‑causing bacteria.
How Bad Bacteria Slip Past Our Defenses
The intestines are lined with a thick, slippery coat of mucus. This coat keeps germs away from the gut walls and helps good bacteria stay in balance.
To cause disease, harmful bacteria must first cut through this mucus. They do it with special enzymes that chew the proteins holding the mucus together.
One of these enzymes, called EatA, was first found in disease‑causing E. coli. The new study shows that two similar enzymes – SepA and Pic – made by Shigella and other diarrhea bugs work the same way.
One Antibody Can Block Many Bugs
Antibodies are tiny proteins the immune system makes to grab onto specific targets. The team discovered that an antibody that blocks EatA also stops SepA and Pic.
All three enzymes share a tiny region. The antibody latches onto that region, shutting down the “mucus‑chewing” tools the bacteria need to infect us.
Proof From Children in Bangladesh
Earlier work with children in Dhaka showed that kids who naturally had antibodies against EatA got sick less often. Kids without those antibodies were more likely to catch the disease.
Enterotoxigenic E. coli also causes food‑borne outbreaks in the United States. It is hard for many labs to tell the bad strain from harmless ones, so many cases are missed.
Relying on antibiotics to treat these infections adds to the global problem of drug‑resistant bacteria.
Next Steps Toward a New Vaccine
The researchers are now working on a vaccine that teaches the body to make the protective antibody before infection happens.
“These bugs have learned how to break through our mucus,” said lead scientist Dr. Fleckenstein. “If we can block that first step, we can stop the illness before it starts.”