Identification of the flagellar antigens of Vibrio cholerae El Tor and their role in protection.

Antiserum to the surface antigens of the wild-type flagellate strain KB207 of Vibrio cholerae El Tor was absorbed with isogenic aflagellate mutant CD12. Antibodies remaining in the absorbed serum exhibited specificity to KB207 but not to CD12 and inhibited motility of KB207. Proteins from cell-free lysates of KB207 and CD12 were analysed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. CD12 differed from KB207 in the absence of two proteins of 40 and 38 kDa. These proteins were detected in KB207 when electrophoretically separated proteins were immunoblotted with unabsorbed and absorbed sera. These two proteins were isolated by immunoaffinity chromatography using purified antibodies from absorbed serum. Although antigenic, the 40 and 38 kDa proteins did not induce protection against cholera in the rabbit ileal loop model.