Protection mediated by antibodies to iron-regulated outer-membrane proteins of S. typhi in a mouse peritonitis model
Iron limitation induces the expression of iron-regulated outer-membrane proteins, which are not expressed under iron sufficient growth conditions. In the present study, these proteins were purified in order to evaluate their protective potential in the experimental model. Anti IROMPs antiserum was raised in rabbits. In mice, passively transferred anti-IROMPs antibodies provided 60% protection against the serovar Typhi challenge dose (9.6 LD50). The hyperimmune serum containing anti-IROMPs antibodies were also found to be bactericidal in the presence of complement whereas no bacterial killing was observed with pre-immunized serum. Bactericidal titre of anti-IROMPs serum was fond to be 2000 as more than 50% killing was observed with serum diluted to 1:2000. The role of IROMPs was assessed in actively-immunized mice followed by challenge with serovar Typhi. These proteins provided protection in 90% mice against challenge (480 LD50) with the pathogen. The levels of isotypes of antibodies (IgG, IgM & IgA) in the sera and secretory antibodies (sIgA) in the gut fluid of immunized mice correlated with the protection. This study, thus indicates that anti IROMPs antibodies may play an important role in providing protection at systemic as well as at mucosal level.
Keywordsantibodies IROMPs protection Salmonella
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- 13.Weinberg ED: Iron withholding: A defense against infection and disease. Physiol Rev 4: 65–102, 1984Google Scholar
- 14.Rishi P, Woodward CL, Kim WK, Ricke SC: Salmonella enterica serovar Typhimurium hilA-lacZY fusion gene response to iron chelation in rich and minimal media. J Environ Sci Health B39(5–6): 861–870, 2004Google Scholar
- 24.Sood S, Rishi P, Sharma S, Sapru S, Ganguly NK: Expression of iron regulated outer membrane proteins in S. typhi grown in soild media. Med Sci Res 27: 6–13, 1999Google Scholar
- 30.Piotrowicz BJ, Edlin SE, McCartney AC: A sensitive chromogenic limulus amoebocyte lysate microassay for detection of endotoxin in human plasma and in water. Bact Microbiol Hyg A260: 108–112, 1985Google Scholar
- 33.Reed IJ, Muench HA: A simple method of estimating fifty percent points. Am J Hyg 27: 493–499, 1998Google Scholar
- 35.Forrest BD: Identification of an intestinal immune response using peripheral blood lymphocytes. Lancet 16: 81–83, 1988Google Scholar
- 36.Kuby J: In: Immunology, 3rd edn., Freedman WH and Co., New York, 1997Google Scholar
- 37.Szu SC, Stone AL, Robins FD, Schmerrson R, Robbins JB: Vi-capsular polysaccharide protein conjugates for prevention of typhoid fever. J Exp Med 66: 1510–1517, 1987Google Scholar