Vibrio cholerae CVD103-HgR live oral attenuated vaccine: construction, safety, immunogenicity, excretion and non-target effects.

In many controlled studies, CVD103-HgR has been shown to be safe and immunogenic and to offer a significant degree of protection against experimental cholera after a single dose. Its minimal excretion and limited ability to compete and survive in various ecosystems indicate that this strain presents little risk to the environment. Furthermore, the potential of CVD103-HgR to regain virulence by acquisition of the CT A or LT A gene is extremely remote even under optimal conditions. Therefore, CVD103-HgR possesses those traits desired in a live oral attenuated vaccine produced by recombinant DNA technology.