title: Safety, immunogenicity, and efficacy of recombinant live oral cholera vaccines, CVD 103 and CVD 103-HgR.
abstract: The genes encoding the A (toxic) subunit of cholera toxin were deleted from pathogenic Vibrio cholerae O1 strain 569B by recombinant techniques, leaving intact production of immunogenic, non-toxic B subunit. The resultant strain, CVD 103, evaluated for safety, immunogenicity, and efficacy as a live oral vaccine, was highly attenuated and elicited strong antibacterial and antitoxic immune responses; a single dose significantly protected volunteers against challenge with pathogenic V cholerae O1 of either serotype or biotype. A further derivative, CVD 103-HgR, which has an Hg++-resistance gene to differentiate it from wild-type vibrios, was also well-tolerated, immunogenic, and protective; moreover, faecal excretion of this derivative was significantly lower than that of CVD 103, which should minimise environmental spread of the vaccine. CVD 103-HgR is a candidate for expanded clinical trials in endemic areas.
mesh_terms: D000284:Administration, Oral; D000328:Adult; D002771:Cholera / Q000517:prevention & control*; D022121:Cholera Vaccines / Q000008:administration & dosage / Q000009:adverse effects / Q000145:classification / Q000276:immunology; D002986:Clinical Trials as Topic; D004311:Double-Blind Method; D004341:Drug Evaluation; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis; D013997:Time Factors; D014611:Vaccination / Q000009:adverse effects; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000009:adverse effects / Q000145:classification / Q000276:immunology; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000009:adverse effects / Q000145:classification / Q000276:immunology; D014734:Vibrio cholerae / Q000145:classification / Q000235:genetics / Q000276:immunology
chemical_list: D022121:Cholera Vaccines; D007074:Immunoglobulin G; D014613:Vaccines, Attenuated; D014614:Vaccines, Synthetic