| abstract |
An immunogenic detoxified protein comprising the amino acid sequence of subunit A of a cholera toxin (CT-A) or a fragment thereof in which at least one amino acid is substituted with another amino acid characterized in that, in purified form, the immunogenic detoxified protein exhibits a residual toxicity greater than 10000 fold lower than its naturally occurring counterpart. In the described embodiment, the amino acid at, or in a position corresponding to Pro-106 is replaced with another amino acid. The immunogenic detoxified protein is useful as vaccine for Vibrio cholerae and is produced by recombinant DNA means by site-directed mutagenesis. |