title: Antibodies to the Vi capsule of Salmonella Typhi in the serum of typhoid patients and healthy control subjects from a typhoid endemic region.
abstract: BACKGROUND
  There is very little published data on the antibody response to the Vi capsular polysaccharide (Vi-CPS) of S. Typhi during naturally acquired typhoid fever in an endemic area.
  
  
  METHODS
  An indirect ELISA, using tyraminated, purified Vi-CPS, was used to assay anti-Vi-CPS antibodies from typhoid fever cases and controls living in the Ho Chi Minh City and Mekong Delta region of Viet Nam.
  
  
  RESULTS
  Antibody response to Vi-CPS is significantly higher in typhoid patients who have been ill for more than two weeks than those who are in the first two weeks of illness. The anti-Vi-CPS response is similar for adults and children. Anti-Vi-CPS antibodies can be detected in the sera of non-typhoid patients. The frequency with which this occurs increases with age, probably reflecting increased exposure to S. Typhi.
  
  
  CONCLUSIONS
  Anti-Vi_CPS is elicited in persons infected with S. Typhi but only after a prolonged duration of illness. Vaccine trials have shown anti-Vi-CPS antibodies to be protective; thus early treatment of typhoid patients, i.e. in the first two week of illness before the Vi-CPS response is elicited, may inhibit the development of this protective immune response.
authors.affiliation: Department of Biochemistry, Imperial College of Science, Technology and Medicine, London, United Kingdom.
authors.forename: Deborah
authors.initials: D
authors.lastname: House
authors.forename: Vo A
authors.initials: VA
authors.lastname: Ho
authors.forename: To S
authors.initials: TS
authors.lastname: Diep
authors.forename: Nguyen T
authors.initials: NT
authors.lastname: Chinh
authors.forename: Phan V
authors.initials: PV
authors.lastname: Bay
authors.forename: Ha
authors.initials: H
authors.lastname: Vinh
authors.forename: Minh
authors.initials: M
authors.lastname: Duc
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Parry
authors.forename: Gordon
authors.initials: G
authors.lastname: Dougan
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: White
authors.forename: Jeremy J
authors.initials: JJ
authors.lastname: Farrar
authors.forename: Tran Tinh
authors.initials: TT
authors.lastname: Hien
authors.forename: John
authors.initials: J
authors.lastname: Wain
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000907:Antibodies, Bacterial / Q000097:blood*; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D019353:Endemic Diseases; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D011135:Polysaccharides, Bacterial / Q000276:immunology*; D012485:Salmonella typhi / Q000276:immunology*; D014435:Typhoid Fever / Q000276:immunology*; D014744:Vietnam / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000907:Antibodies, Bacterial; D011135:Polysaccharides, Bacterial; C054154:capsular polysaccharide, Salmonella