Oral priming with Salmonella Typhi vaccine strain CVD 909 followed by parenteral boost with the S. Typhi Vi capsular polysaccharide vaccine induces CD27+IgD-S. Typhi-specific IgA and IgG B memory cells in humans |
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Authors: | Wahid Rezwanul Pasetti Marcela F Maciel Milton Simon Jakub K Tacket Carol O Levine Myron M Sztein Marcelo B |
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Affiliation: | Center for Vaccine Development, Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MD, USA. |
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Abstract: | Attenuated live oral typhoid vaccine candidate CVD 909 constitutively expresses Salmonella Typhi capsular polysaccharide antigen (Vi). A randomized, double-blind, heterologous prime-boost clinical study was conducted to determine whether immunity to licensed parenteral Vi vaccine could be enhanced by priming with CVD 909. Priming with CVD 909 elicited higher and persistent, albeit not significant, anti-Vi IgG and IgA following immunization with Vi, than placebo-primed recipients. Vi-specific IgA B memory (B(M)) cells were significantly increased in CVD 909-primed subjects. S. Typhi-specific LPS and flagella IgA B(M) cells were observed in subjects immunized with CVD 909 or with the licensed Vi-negative oral typhoid vaccine Ty21a. CVD 909-induced B(M) cells exhibited a classical B(M) phenotype (i.e., CD3(-)CD19(+)IgD(-)CD27(+)). This is the first demonstration of classical B(M) cells specific for bacterial polysaccharide or protein antigens following typhoid immunization. The persistent IgA B(M) responses demonstrate the capacity of oral typhoid vaccines to prime mucosally relevant immune memory. |
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Keywords: | ALS, Antibody in Lymphocyte Supernatant ASC, antibody secreting cell BM, memory B cells CMI, cell-mediated immunity CI, confidence interval GMT, geometric mean titer LPS, lipopolysaccharide PBMC, peripheral blood mononuclear cells SFC, spot forming cells T-D, T cell-dependent T-I, T cell-independent |
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