The bacteria enterotoxigenic E. coli and Shigella together cause hundreds of millions of infections each year and are among the leading causes of diarrheal death, especially in children. Decades of vaccine development efforts have come up short, in part because the usual vaccine targets vary too much from one strain to the next. Now, new research from Washington University School of Medicine in St. Louis points to a shared biological feature of these gut pathogens that could lead to a vaccine that protects against both.

Researchers at WashU Medicine, along with collaborators at the University of Missouri and the International Centre for Diarrhoeal Disease Research in Bangladesh, found that enterotoxigenic E. coli (the leading cause of travelers’ diarrhea), Shigella and other diarrhea-causing pathogens rely on three closely related enzymes to get through the gut’s protective mucus layer and cause infection. Based on samples from infected patients and volunteers exposed to the bugs, the team showed that antibodies targeting one shared region of these enzymes can neutralize all three biomolecules and block the bacteria from penetrating the mucus barrier of the intestines.

The results, which appear in PNAS, point to the potential for a single combination vaccine against these major causes of severe diarrhea.