Scientists discover a shared weakness in deadly gut bacteria for a universal vaccine

Researchers at Washington University School of Medicine in St. Louis have uncovered a shared weakness in harmful gut bacteria. Their findings could pave the way for a single vaccine to combat multiple diarrheal pathogens, including ETEC and Shigella. The team identified three closely related enzymes—EatA, SepA, and Pic—produced by enterotoxigenic E. coli (ETEC), Shigella, and other diarrheal bacteria. These enzymes help the bacteria break down the protective mucus lining in the human gut, allowing infections to take hold.

Using cryo-electron microscopy, the scientists pinpointed the exact binding site of antibodies that neutralise EatA. These antibodies also block SepA and Pic, revealing a conserved region shared across the enzymes. This discovery suggests a common vulnerability that could be targeted by a vaccine.

ETEC has caused recent foodborne outbreaks in industrialised nations, including the US. Diagnosis is challenging because pathogenic and non-pathogenic strains are hard to tell apart. Meanwhile, overuse of antibiotics to treat these infections is speeding up resistance.

The study also found that children in Dhaka, Bangladesh, who naturally developed antibodies against EatA were protected from severe diarrhoea. This supports the potential of a vaccine targeting this shared feature. The research team is now working to turn these molecular insights into practical vaccine candidates for preclinical trials. A successful vaccine could reduce reliance on antibiotics and help control outbreaks caused by these bacteria. The shared epitope among the enzymes offers a promising path for broad protection.