Effect of oral immunization with the Ty21a typhoid vaccine on local and systemic immune responses and the gut microbiota in adults. gut metagenome

The resident microbial consortia of the human gastrointestinal tract play an integral role in modulating the immune response both locally and systemically. However, detailed information regarding the correlates of protective immunity after vaccine administration in relation to the gastrointestinal microbiota is absent. In this study, the licensed oral attenuated typhoid vaccine Ty21a was administered in a clinical study to investigate whether oral immunization resulted in alterations of the microbiota and identify immune responses that may alter microbiota composition. The gastrointestinal microbiota was characterized from stool samples by pyrosequencing of the bacterial 16S ribosomal gene.