Antibodies to the Vi capsule of Salmonella Typhi in the serum of typhoid patients and healthy control subjects from a typhoid endemic region

• Main Author: Deborah House1,2, Vo A. Ho4,To S. Diep5, Nguyen T. Chinh6, Phan V. Bay4, Ha Vinh5, Minh Duc4, Christopher M. Parry2,3, Gordon Dougan1, Nicholas J. White2,3, Jeremy J. Farrar2,3, Tran Tinh Hien5, John Wain2,3
• Format: Article
• Language: English
• Published: The Journal of Infection in Developing Countries 2008-08-01
• Series: Journal of Infection in Developing Countries
• Subjects: capsule; Salmonella Typhi; typhoid fever; antibodies; Viet Nam; Vietnam
• Online Access: http://www.jidc.org/issn1972-2680/current-issue/68-vol-2-no-4-august-2008/169-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.Methodology: 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.