Infection with ETEC is a major cause of diarrheal disease in underdeveloped nations, especially among children. It causes 210 million diarrhea episodes and approximately 380,000 deaths worldwide annually. In addition, it is the leading cause of travelers’diarrhea. ETEC is transmitted by food or water contaminated with animal or human feces.
ETEC attach via hair-like fimbriae (colonization factor antigens) to specific receptors on the surface of enterocytes in the intestinal lumen. ETEC then produce toxins which stimulate the lining of the intestines to secrete excessive fluid, thus producing diarrhea. ETEC strains produce heat stable toxin (ST), heat labile toxin (LT), or both.
Several vaccine strategies against ETEC are being explored. They include the following:
- Purified colonization factors
- LT-only or LT-ST toxoids
- Recombinant CTB combined with five strains of formalin-killed ETEC cells that express various colonization factors
- Live attenuated Shigella vectors expressing ETEC fimbrial and LT antigens
- Oral live attenuated Vibrio cholerae vectoring colonization factor antigens
- Oral, live, attenuated ETEC strains produced by mutagenesis of the aroC, ompR, ompC, and/or ompF genes
- Colonization factor antigens encapsulated in biodegradable microspheres
- Naked DNA vaccines
- Expression of the B subunit of LT (LTB) in bananas, tobacco, potatoes, and tomatoes
- Edible transgenic plants expressing cholerea toxin B subunit (CTB), which is similar to LTB.
- Fimbrial adhesion antigen CS6 and LT, delivered by transcutaneous patch
- Oral live attenuated Salmonella typhi expressing LTB and some CFAs
- Non-living oral toxoids consisting of synthetic ST linked to the LTB
- Milk-derived antibodies against CFAs
Initiative for Vaccine Research
Division of Foodborne, Bacterial and Mycotic Diseases
Here is a link to information about participating in vaccine studies for Traveler’s Diarrhea at the CIR.