For the ETEC Intestinal colonization model, normal flora is eliminated with streptomy- cin and cimetidine is used for stomach deacidification. Mice are then inoculated with ETEC H10407 by gastric gavage and colonization is examined at different time points post chal- lenge by measurement of CFUs in the intestine. Bacterial shedding as well as antibody re- sponse can be measured in stool samples. Lethality endpoint can be determined using high dose challenge.