Antigen-Specific lgA B Memory Cell Responses to Shigella Antigens Elicited in Volunteers Immunized with Live Attenuated Shigella flexneri 2a Oral Vaccine Candidates

摘要

We studied the induction of antigen-specific lgA memory B cells (BM) in volunteers who received live attenuated Shigella flexneri 2a vaccines. Subjects ingested a single oral dose of 107 , 108 or 109 CFU of S. flexneri 2a with deletions in guaBA (CVD 1204) or in guaBA, set and sen (CVD 1208). Antigen- specific serum and stool antibody responses to LPS and lpa B were measured on days 0, 7, 14, 28 and 42. lgA BM cells specific to LPS, lpa Band totallgA were assessed on days 0 and 28. We show the induction of significant LPS-specific lgA BM cells in anti-LPS lgA seroresponders. Positive correlations were found between anti-LPS lgA BM cells and anti-LPS lgA in serum and stool; lgA BM cell responses to lpaB were also observed. These BM cell responses are likely play an important role in modulating the magnitude and longevity of the humoral response.