Identification of LPS-specific MAbs in clonally expanded cells that have marked heterogeneity in somatic hypermutation and affinity toward a historical V. cholerae serotype. (A) The repertoire breadth of plasmablast-derived heavy chain sequences is indicated. For each patient, the number at the center of each pie chart indicates the number of heavy-chain sequences evaluated. Clonal expansions (defined as two or more sequences sharing the same VDJ rearrangement and junctional diversity) are shown as expanded sections of the pie chart. Colors denote antibody specificity as described in the panel legend. The Ig isotypes identified within each clonal expansion are shown adjacent to each section (G, IgG; A, IgA; M, IgM). (B) A comparison of Ig heavy-chain somatic hypermutation, relative to the closest germline sequence, with antibody specificity. (C) Antibody affinity to LPS as measured by ELISA is shown as the minimum MAb concentration required for 3 times the background signal of sample dilution buffer. (D) Epidemiological prevalence of the O1 serotypes Ogawa and Inaba in the patient cohorts at icddr,b in Dhaka. Our study was conducted during an extended period with an extremely low prevalence of the Inaba serotype.