T cell mediated immunity induced by the live-attenuated Shigella flexneri 2a vaccine candidate CVD 1208S in humans
JournalJournal of Translational Medicine
PublisherBioMed Central Ltd.
MetadataShow full item record
AbstractBackground: Shigellosis persists as a public health problem worldwide causing ~ 165,000 deaths every year, of which ~ 55,000 are in children less than 5 years of age. No vaccine against shigellosis is currently licensed. The live-attenuated Shigella flexneri 2a vaccine candidate CVD 1208S (S. flexneri 2a; ΔguaBA, Δset, Δsen) demonstrated to be safe and immunogenic in phase 1 and 2 clinical trials. Earlier reports focused on humoral immunity. However, Shigella is an intracellular pathogen and therefore, T cell mediated immunity (T-CMI) is also expected to play an important role. T-CMI responses after CVD 1208S immunization are the focus of the current study. Methods: Consenting volunteers were immunized orally (3 doses, 108 CFU/dose, 28 days apart) with CVD 1208S. T-CMI to IpaB was assessed using autologous EBV-transformed B-Lymphocytic cell lines as stimulator cells. T-CMI was assessed by the production of 4 cytokines (IFN-γ, IL-2, IL-17A and TNF-α) and/or expression of the degranulation marker CD107a in 14 volunteers (11 vaccine and 3 placebo recipients). Results: Following the first immunization, T-CMI was detected in CD8 and CD4 T cells obtained from CVD 1208S recipients. Among CD8 T cells, the T effector memory (TEM) and central memory (TCM) subsets were the main cytokine/CD107a producers/expressors. Multifunctional (MF) cells were also detected in CD8 TEM cells. Cells with 2 and 3 functions were the most abundant. Interestingly, TNF-α appeared to be dominant in CD8 TEM MF cells. In CD4 T cells, TEM responses predominated. Following subsequent immunizations, no booster effect was detected. However, production of cytokines/expression of CD107a was detected in individuals who had previously not responded. After three doses, production of at least one cytokine/CD107a was detected in 8 vaccinees (73%) in CD8 TEM cells and in 10 vaccinees (90%) in CD4 TEM cells. Conclusions: CVD 1208S induces diverse T-CMI responses, which likely complement the humoral responses in protection from disease. Trial registration: This study was approved by the Institutional Review Board and registered on ClinicalTrials.gov (identifier NCT01531530). Copyright 2018 The Author(s).
SponsorsThis work was supported, in part, by Grant #U19 AI082655 (CCHI, Cooperative Center on Human Immunology -CCHI-) to MBS and by an UM-CCHI Pilot project, a component of Grant U19 AI082655 to FRT, from the National Institutes of Health (NIH), National Institute of Allergy and Infectious Diseases (NIAID). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institute of Allergy and Infectious Diseases, the National Institutes of Health, NIAID, NIH.
Identifier to cite or link to this itemhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-85043592962&doi=10.1186%2fs12967-018-1439-1&partnerID=40&md5=1d54fa25f91ff6c67499d0a87adf6b6e; http://hdl.handle.net/10713/9091