622. Increased IgA Coating of Gut Microbes After Administration of Killed, Whole-Cell Oral Cholera Vaccine

Cholera vaccines are recommended for use in outbreaks to prevent infections and reduce severity of disease. Variable immune responses are observed after administration of killed, whole-cell cholera vaccines, and limited data suggest that the gut microbiome may be one factor influencing immune responses to vaccination. Methods. We used microbial DNA sequencing of stool and serum vibriocidal titers to examine the gut microbiome and immune responses to vaccination at day 0, 7, 17 and 44 in adult vaccine recipients in Dhaka, Bangladesh. Using flow cytometry-based bacterial cell sorting, we identified IgA-coated gut microbes in stool before and after vaccination in a subset of patients. Results. Vibriocidal titer magnitude and kinetics were used to classify participants. Within 17 days of vaccination, 86/89…