Single-Cell Analysis of the Plasmablast Response to Vibrio cholerae Demonstrates Expansion of Cross-Reactive Memory B Cells

• Main Authors: Robert C. Kauffman, Taufiqur R. Bhuiyan, Rie Nakajima, Leslie M. Mayo-Smith, Rasheduzzaman Rashu, Mohammad Rubel Hoq, Fahima Chowdhury, Ashraful Islam Khan, Atiqur Rahman, Siddhartha K. Bhaumik, Levelle Harris, Justin T. O'Neal, Jessica F. Trost, Nur Haq Alam, Algis Jasinskas, Emmanuel Dotsey, Meagan Kelly, Richelle C. Charles, Peng Xu, Pavol Kovááč, Stephen B. Calderwood, Edward T. Ryan, Phillip L. Felgner, Firdausi Qadri, Jens Wrammert, Jason B. Harris
• Format: Article
• Language: English
• Published: American Society for Microbiology 2016-12-01
• Series: mBio
• Online Access: http://mbio.asm.org/cgi/content/full/7/6/e02021-16

We characterized the acute B cell response in adults with cholera by analyzing the repertoire, specificity, and functional characteristics of 138 monoclonal antibodies (MAbs) generated from single-cell-sorted plasmablasts. We found that the cholera-induced responses were characterized by high levels of somatic hypermutation and large clonal expansions. A majority of the expansions targeted cholera toxin (CT) or lipopolysaccharide (LPS). Using a novel proteomics approach, we were able to identify sialidase as another major antigen targeted by the antibody response to Vibrio cholerae infection. Antitoxin MAbs targeted both the A and B subunits, and most were also potent neutralizers of enterotoxigenic Escherichia coli heat-labile toxin. LPS-specific MAbs uniformly targeted the O-specific polysaccharide, with no detectable responses to either the core or the lipid moiety of LPS. Interestingly, the LPS-specific antibodies varied widely in serotype specificity and functional characteristics. One participant infected with the Ogawa serotype produced highly mutated LPS-specific antibodies that preferentially bound the previously circulating Inaba serotype. This demonstrates durable memory against a polysaccharide antigen presented at the mucosal surface and provides a mechanism for the long-term, partial heterotypic immunity seen following cholera.