Dispersin' Escherichia coli all over the gut

Enteroaggregative Escherichia coli (EAEC) is an emerging pathogen that causes endemic and epidemic diarrhea in developing and industrialized countries. The bacteria stick to the surface of the cells lining the gut and release specific toxins that cause the cells to "open the floodgates" and dramatically increase secretion of electrolytes and water into the gut lumen. EAEC form a thick biofilm on the gut surface that is thought to mediate their persistence and ability to cause disease.

A report in the November 4 issue of the Journal of Clinical Investigation now sheds light on how this protective film might be formed. James Nataro and colleagues of the University of Maryland School of Medicine were searching for proteins that contribute to EAEC's success as a human pathogen as well as those that provoke a robust immune response and might serve as vaccines. One of their discoveries was a molecule that they called 'dispersin' to reflect its ability to promote dispersal of the bacteria on surfaces. Dispersin coats the outside of the EAEC bacteria and seems to help them to penetrate the gut mucous layer and make contact with the underlying intestinal cells. In addition, it may help to spread the bacteria across the gut surface and to form the characteristic biofilm.

EAEC is a rapidly emerging pathogen, but vaccine development is in its earliest stages. Dispersin's position on the bacterial surface (where it is accessible to immune cells) and its presence in the vast majority of EAEC strains make it a potential candidate for vaccine development. Findings by Nataro and colleagues that dispersin can provoke a strong immune response in EAEC-challenged human volunteers, underline its considerable promise.

CONTACT:
James P. Nataro
Center For Vaccine Development
Depts. of Peds., Microbiol., & Immunol.
Univ. of Maryland School Of Medicine
685 W. Baltimore Street
Baltimore, MD 21201
USA
PHONE: 410-706-5328
FAX: 410-706-6205
E-mail: jnataro@medicine.umaryland.edu

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