Antibody against the capsule of Vibrio cholerae O139 protects against experimental challenge

Antiserum to the capsular polysaccharide of an opaque variant of Vibrio cholerae O139 strain MDO-12 recognizes capsular antigen in three different colonial variants of the strain, although the amount of recognition varies with the extent of opacity. The anti-capsular-polysaccharide serum, at subagglutinating doses, protected suckling mice against challenge with both the most opaque variant and the most translucent variant. Further studies indicated that the protection was associated with inhibition of intestinal colonization by the vibrios. These results thus highlight the potential importance of the capsule in immunoprophylaxis against cholera caused by V. cholerae O139.