期刊
FRONTIERS IN IMMUNOLOGY
卷 10, 期 -, 页码 -出版社
FRONTIERS MEDIA SA
DOI: 10.3389/fimmu.2019.02582
关键词
typhoid fever; Salmonella Typhi (S; Typhi); Vi polysaccharide; correlates of protection (CoP); humoral immunity; vaccination; antibody; avidity
类别
资金
- Bill & Melinda Gates Foundation [OPP1084259]
- European Commission FP7 grant Advanced Immunization Technologies (ADITEC)
- NIHR Oxford Biomedical Research Center
- Bill and Melinda Gates Foundation [OPP1151372]
- National Institutes of Health (NIH) [T32 AI 52077]
- Duke University
- Bill and Melinda Gates Foundation [OPP1084259, OPP1151372] Funding Source: Bill and Melinda Gates Foundation
Vaccination against Salmonella Typhi using the Vi capsular polysaccharide, a T-cell independent antigen, can protect from the development of typhoid fever. This implies that antibodies to Vi alone can protect in the absence of a T cell-mediated immune response; however, protective Vi antibodies have not been well-characterized. We hypothesized that variability in the biophysical properties of vaccine-elicited antibodies, including subclass distribution and avidity, may impact protective outcomes. To interrogate the relationship between antibody properties and protection against typhoid fever, we analyzed humoral responses from participants in a vaccine efficacy (VE) trial using a controlled human infection model (CHIM) who received either a purified Vi polysaccharide (Vi-PS) or Vi tetanus toxoid conjugate (Vi-TT) vaccine followed by oral challenge with live S. Typhi. We determined the avidity, overall magnitude, and vaccine-induced fold-change in magnitude from before immunization to day of challenge of Vi IgA and IgG subclass antibodies. Amongst those who received the Vi-PS vaccine, Vi IgA magnitude (FDR p = 0.01) and fold-change (FDR p = 0.02) were significantly higher in protected individuals compared with those individuals who developed disease (diagnosed). In the Vi-TT vaccine group, the responses of protected individuals had higher fold-change in Vi IgA (FDR p = 0.06) and higher Vi IgG1 avidity (FDR p = 0.058) than the diagnosed Vi-TT vaccinees, though these findings were not significant at p < 0.05. Overall, protective antibody signatures differed between the Vi-PS and Vi-TT vaccines, thus, we conclude that although the Vi-PS and Vi-TT vaccines were observed to have similar efficacies, these vaccines may protect through different mechanisms. These data will inform studies on mechanisms of protection against typhoid fever, including identification of antibody effector functions, as well as informing future vaccination strategies.
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