The avidity of
antibodies to specific
antigens and the relationship of avidity to memory B cell responses to these
antigens have not been studied in patients with
cholera or those receiving oral
cholera vaccines. We measured the avidity of
antibodies to
cholera toxin B subunit (CTB) and Vibrio cholerae O1
lipopolysaccharide (LPS) in Bangladeshi adult
cholera patients (
n = 30), as well as vaccinees (
n = 30) after administration of two doses of a killed oral
cholera vaccine. We assessed antibody and memory B cell responses at the acute stage in patients or prior to vaccination in vaccinees and then in follow-up over a year. Both patients and vaccinees mounted CTB-specific
IgG and
IgA antibodies of high avidity. Patients showed longer persistence of these
antibodies than vaccinees, with persistence lasting in patients up to day 270 to 360. The avidity of LPS-specific
IgG and
IgA antibodies in patients remained elevated up to 180 days of follow-up. Vaccinees mounted highly avid LPS-specific
antibodies at day 17 (3 days after the second dose of
vaccine), but the avidity waned rapidly to baseline by 30 days. We examined the correlation between
antigen-specific memory B cell responses and avidity indices for both
antigens. We found that numbers of CTB- and LPS-specific memory B cells significantly correlated with the avidity indices of the corresponding
antibodies (P < 0.05; Spearman's ρ = 0.28 to 0.45). These findings suggest that antibody avidity after
infection and immunization is a good correlate of the development and maintenance of memory B cell responses to Vibrio cholerae O1
antigens.