Vaccines against enterotoxigenic Escherichia coli

Abstract

Enterotoxigenic Escherichia coli (ETEC) is a major cause of diarrhea among children less than 3 years of age in developing countries and in travelers to these areas. The key pathogenic mechanisms that contribute to the pathogenesis of ETEC are the production of colonization factors (CFs) and a heat-labile enterotoxin (LT) and/or a heat-stable enterotoxin. To provide broad-spectrum protection, an ETEC vaccine should, most likely, contain the most prevalent fimbrial antigens, that is, CF antigen I and CS1–CS6, and/or a LT toxoid. Different strategies have been taken to deliver ETEC fimbriae and toxin antigens to the human immune system to elicit strong mucosal, in particular, intestinal immune responses that are considered to be of prime importance for protection against ETEC disease. There has been some promise when testing different ETEC candidate vaccines for protection against diarrhea in adult travelers. However, no ETEC candidate vaccine has been shown to be effective in the most important target group, which is infants and young children in endemic areas. Against this background, intense efforts are in progress to try to improve the immunogenicity of different available candidate vaccines, as well as to develop new types of ETEC vaccines.

Keywords::

• colonization factor
• diarrhea
• enterotoxigenic Escherichia coli
• inactivated vaccine
• live vaccine
• oral vaccine
• toxoid

Financial & competing interests disclosure

The authors have collaborations with Crucell/SBL Vaccin on the development of the rCTB-CF ETEC vaccines. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.