title: Kinetics of the natural, humoral immune response to Salmonella enterica serovar Typhi in Kathmandu, Nepal.
abstract: Typhoid fever is a major public health problem in developing countries, conservatively estimated to occur in 17 million cases and be responsible for 200,000 deaths annually. We investigated the acquisition of natural immunity to Salmonella enterica serovar Typhi in a region where typhoid is endemic by testing sera from an age-stratified sample of 210 healthy participants in Kathmandu, Nepal, for bactericidal activity toward S. Typhi and for anti-Vi capsular polysaccharide antibodies. Bactericidal titers in children were significantly lower than those in newborns and adults (P < 0.0001). Anti-S. Typhi bactericidal geometric mean titers were age dependent, increasing 10-fold during childhood. Anti-Vi polysaccharide antibody geometric mean concentrations were also lower in children than in adults. Data presented here indicate the possibility of a relationship between low levels of bactericidal activity toward S. Typhi in serum and susceptibility to disease, as observed for other polysaccharide-encapsulated bacteria. Bactericidal antibody may be a marker of protective immunity against S. Typhi.
authors.affiliation: Oxford Vaccine Group, University Department of Paediatrics, University of Oxford, Oxford, United Kingdom. anoopdoc@yahoo.com
authors.forename: Anoop S
authors.initials: AS
authors.lastname: Pulickal
authors.forename: Samir
authors.initials: S
authors.lastname: Gautam
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Clutterbuck
authors.forename: Stephen
authors.initials: S
authors.lastname: Thorson
authors.forename: Buddha
authors.initials: B
authors.lastname: Basynat
authors.forename: Neelam
authors.initials: N
authors.lastname: Adhikari
authors.forename: Katherine
authors.initials: K
authors.lastname: Makepeace
authors.forename: Sjoerd
authors.initials: S
authors.lastname: Rijpkema
authors.forename: Ray
authors.initials: R
authors.lastname: Borrow
authors.forename: Jeremy J
authors.initials: JJ
authors.lastname: Farrar
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Pollard
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000907:Antibodies, Bacterial / Q000097:blood*; D000942:Antigens, Bacterial; D001770:Blood Bactericidal Activity; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D005312:Fetal Blood / Q000276:immunology; D006801:Humans; D056724:Immunity, Humoral; D007113:Immunity, Innate; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D009390:Nepal / Q000453:epidemiology; D011135:Polysaccharides, Bacterial / Q000276:immunology; D011247:Pregnancy; D012485:Salmonella typhi / Q000276:immunology*; D014435:Typhoid Fever / Q000453:epidemiology* / Q000276:immunology*; D055815:Young Adult
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D011135:Polysaccharides, Bacterial; C054154:capsular polysaccharide, Salmonella