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.
Author(s): Wahid R, Pasetti MF, Maciel M Jr, Simon JK, Tacket CO, Levine MM, Sztein MB.
Affiliation(s): Center for Vaccine Development, Department of Pediatrics, University of Maryland
School of Medicine, Baltimore, MD, USA.
Publication date & source: 2011, Clin Immunol. , 138(2):187-200
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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