Antibodies to the Vi capsule of Salmonella Typhi in the serum of typhoid patients and healthy control subjects from a typhoid endemic region.
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.
House
Deborah
D
Department of Biochemistry, Imperial College of Science, Technology and Medicine, London, United Kingdom.
Ho
Vo A
VA
Diep
To S
TS
Chinh
Nguyen T
NT
Bay
Phan V
PV
Vinh
Ha
H
Duc
Minh
M
Parry
Christopher M
CM
Dougan
Gordon
G
White
Nicholas J
NJ
Farrar
Jeremy J
JJ
Hien
Tran Tinh
TT
Wain
John
J
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
D000907:Antibodies, Bacterial; D011135:Polysaccharides, Bacterial; C054154:capsular polysaccharide, Salmonella