Cell-mediated immunity and antibody responses elicited by attenuated Salmonella enterica Serovar Typhi strains used as live oral vaccines in humans.
The development of improved typhoid vaccines is a high global public health priority. However, their development has been hampered by a lack of information regarding the specific determinants of protective immunity to Salmonella enterica serovar Typhi (S. Typhi) infection in humans. Although antibodies to S. Typhi O, H, and Vi appear to be involved in protection against S. Typhi infection, it is unknown whether such antibodies mediate protection, act in conjunction with other adaptive responses, or serve as a surrogate for the presence of other, more dominant protective immune responses (e.g., cell-mediated immunity [CMI]). CMI responses elicited by immunization of subjects with attenuated S. Typhi oral vaccines include lymphoproliferation; production of type 1 cytokines (e.g., interferon- gamma and tumor necrosis factor- alpha ); and classical major histocompatibility complex (MHC) class Ia-restricted and novel, nonclassical MHC class Ib (human leukocyte antigen [HLA]-E)-restricted CD8(+) cytotoxic T cell responses. In sum, human immunity to S. Typhi elicited by immunization is unexpectedly broad and complex. However, the immunologic correlates of protection remain largely undefined.
Sztein
Marcelo B
MB
Center for Vaccine Development and Departments of Pediatrics and Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA. msztein@medicine.umaryland.edu
D000915:Antibody Affinity; D000942:Antigens, Bacterial / Q000276:immunology; D006801:Humans; D007111:Immunity, Cellular; D007074:Immunoglobulin G; D011135:Polysaccharides, Bacterial / Q000276:immunology*; D012485:Salmonella typhi / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology; D014436:Typhoid-Paratyphoid Vaccines / Q000276:immunology*; D014613:Vaccines, Attenuated / Q000276:immunology
D000942:Antigens, Bacterial; D007074:Immunoglobulin G; D011135:Polysaccharides, Bacterial; D014436:Typhoid-Paratyphoid Vaccines; D014613:Vaccines, Attenuated; C057664:Vi polysaccharide vaccine, typhoid