The cholera vaccine prototype IEM101 has been evaluated
in animal models and shown to be safe and protective
againstV. cholerae [18]. Single dose vaccination in volunteers
showed that IEM101 could colonize in intestine for 4–9 days
and elicited protective serum and mucosal immunity with
no apparent side reactions [18]. However, there is no antitoxic
response due to the absence of ctxAB genes in IEM101.
To enhance its immuogenicity toxin subunit gene ctxB was
integrated in the chromosome of IEM101.