Pathogenicity of enterotoxigenic Escherichia coli in Caenorhabditis elegans as an alternative model host.

Enterotoxigenic Escherichia coli (ETEC), one of the diarrheagenic E. coli, is the most common cause of diarrhea in developing country, and in travelers to those areas. In this study, Caenorhabditis elegans was used as an alternative model host to evaluate ETEC infections. The ETEC strain ETEC1, which was isolated from a patient with diarrhea, possessed enterotoxins STh, LT1, and EAST1 and colonization factors CS2 and CS3. Live ETEC1 shortened the lifespan and body size of C. elegans in association with increased expression of enterotoxin genes and intestinal colonization. In contrast, heat-killed ETEC1 did not affect the lifespan of C. elegans. C. elegans infected with ETEC1 showed upregulated expression of genes related to insulin-like peptides and host defense responses. These results suggest that ETEC1 exhibits pathogenicity through intestinal colonization and enterotoxin production in C. elegans. This system is useful as an ETEC infection model.