This is a research study about an experimental (investigational) vaccine called ACE527.
ACE527 is a vaccine that is being made to prevent disease from a germ called enterotoxigenic
Escherichia coli (ETEC). This germ causes diarrhea, largely in children living in developing
countries and in travelers to those countries. One purpose of this study is to see if the
vaccine is safe and develops an immune response. Another purpose is to see if it prevents
people from getting sick when exposed to the ETEC germ. This ETEC germ is also experimental