Impact of Immunoglobulin Isotype and Epitope on the Functional Properties of<i>Vibrio cholerae</i>O-Specific Polysaccharide-Specific Monoclonal Antibodies
Robert C. Kauffman, Oluwaseyi Adekunle, Hanyi Yu, Alice Cho, Lindsay E. Nyhoff, Meagan Kelly, Jason B. Harris, Taufiqur Rahman Bhuiyan, Firdausi Qadri, Stephen B. Calderwood, Richelle C. Charles, Edward T. Ryan, Jun Kong, Jens Wrammert
Abstract
Immunity to the severe diarrheal disease cholera is largely mediated by lipopolysaccharide (LPS)-specific antibodies. However, the properties and protective mechanisms of functionally relevant antibodies have not been well defined. Here, we have engineered low and high-affinity LPS-specific antibodies in different immunoglobulin backbones in order to assess the impact of affinity, immunoglobulin isotype, and subclass on binding, vibriocidal, agglutination, and motility inhibition functional properties. Importantly, we found that affinity did not directly dictate functional potency since variants derived from the low-affinity MAbs had comparable agglutination and motility inhibition properties to the potently binding antibodies. This suggests that how the antibody binds sterically may be critical to function. In addition, not only pentameric IgM and dimeric IgA, but also monomeric IgA, was remarkably more potent than their IgG counterparts at inhibiting motility. Finally, analyzing highly purified F(ab) versions of these antibodies, we show that LPS cross-linking is essential for motility inhibition.