Humans surviving cholera develop antibodies against Vibrio cholerae O-specific polysaccharide that inhibit pathogen motility

Charles, R. C.; Kelly, M.; Tam, J. M.; Akter, A.; Hossain, M.; Islam, K.; Biswas, R.; Kamruzzaman, M.; Chowdhurry, F.; Khan, A. I.; Leung, D. T.; Weil, A. A.; LaRocque, R. C.; Bhuiyan, T. R.; Rahman, A.; Mayo-Smith, L.; Becker, R. L.; Vyas, J. M.; Faherty, C. S.; Nickerson, K. P.; Giffen, S.; Ritter, A. S.; Waldor, M. K.; Xu, P.; Kovac, P.; Calderwood, S. B.; Kauffman, R. C.; Wrammert, J.; Qadri, F.; Harris, J. B.; Ryan, E. T.

doi:10.1101/2020.10.08.332551

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bioRxiv · 10.1101/2020.10.08.332551

Humans surviving cholera develop antibodies against Vibrio cholerae O-specific polysaccharide that inhibit pathogen motility

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Abstract

The mechanism of protection against cholera afforded by previous illness or vaccination is currently unknown. We have recently shown that antibodies targeting O-specific polysaccharide (OSP) of Vibrio cholerae correlate highly with protection against cholera. V. cholerae is highly motile and possesses a flagellum sheathed in O-specific polysaccharide (OSP), and motility of V. cholerae correlates with virulence. Using high speed video microscopy, and building upon previous animal-related work, we demonstrate that sera, polyclonal antibody fractions, and OSP-specific monoclonal antibodies recovered from humans surviving cholera block V. cholerae motility at both subagglutinating and agglutinating concentrations. This anti-motility effect is reversed by pre-adsorbing sera and polyclonal antibody fractions with purified OSP; and is associated with OSP-specific but not flagellin-specific monoclonal antibodies. F[ab] fragments of OSP-specific polyclonal antibodies do not inhibit motility, suggesting a requirement for antibody-mediated crosslinking in motility inhibition. We show that OSP-specific antibodies do not directly affect V. cholerae viability, but that OSP-specific monoclonal antibody highly protects against death in the murine cholera model. We used in vivo competitive index studies to demonstrate that OSP-specific antibodies impede colonization and survival of V. cholerae in intestinal tissues, and that this impact is motility-dependent. Our findings suggest that the impedance of motility by antibodies targeting V. cholerae OSP contributes to protection against cholera. IMPORTANCECholera is a severe dehydrating illness of humans caused by Vibrio cholerae. V. cholerae is a highly motile bacterium that has a single flagellum covered in lipopolysaccharide (LPS) displaying O-specific polysaccharide (OSP), and V. cholerae motility correlates with its ability to cause disease. The mechanisms of protection against cholera are not well understood; however, since V. cholerae is a non-invasive intestinal pathogen, it is likely that antibodies that bind the pathogen or its products in the intestinal lumen contribute to protection from infection. Here, we demonstrate that OSP-specific antibodies isolated from humans surviving cholera in Bangladesh inhibit V. cholerae motility and are associated with protection against challenge in a motility-dependent manner.

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Charles, R. C., Kelly, M., Tam, J. M., Akter, A., Hossain, M., Islam, K., Biswas, R., Kamruzzaman, M., Chowdhurry, F., Khan, A. I., Leung, D. T., Weil, A. A., LaRocque, R. C., Bhuiyan, T. R., Rahman, A., Mayo-Smith, L., Becker, R. L., Vyas, J. M., Faherty, C. S., Nickerson, K. P., Giffen, S., Ritter, A. S., Waldor, M. K., Xu, P., Kovac, P., Calderwood, S. B., Kauffman, R. C., Wrammert, J., Qadri, F., Harris, J. B., Ryan, E. T.. 2020-10-09. Humans surviving cholera develop antibodies against Vibrio cholerae O-specific polysaccharide that inhibit pathogen motility. https://doi.org/10.1101/2020.10.08.332551

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