title: Detection of antibodies against Salmonella typhi outer membrane protein (OMP) preparation in typhoid fever patients.
abstract: An indirect ELISA was used to detect antibodies against outer membrane protein preparations (OMPs) from Salmonella typhi. Sera from patients with a definitive diagnosis of typhoid fever (TF) gave a mean absorbance reading, at 414 nm, of 1.52 +/- 0.23 as compared to 0.30 +/- 0.11 for sera from healthy individuals. This gave a positive to negative ratio of absorbance readings of approximately 5.1. Suspected TF patients (no isolation of S. typhi), with positive and negative Widal titers had mean absorbance readings of 1.282 +/00.46 and 0.25 +/- 0.19, respectively. Sera from patients with leptospirosis, rickettsial typhus, dengue fever, and other infections gave mean absorbances of 0.20 +/- 0.08, 0.24 +/- 0.08, 0.27 +/- 0.08, and 0.31 +/- 0.16, respectively. The sensitivity, specificity, positive and negative predictive values were 100%, 94%, 80% and 100%, respectively. The antibody response detected in the definitive TF cases was predominantly IgG in nature and no cross-reactivity was seen with OMP preparations extracted from E. coli. Variable reactivity was noted with OMP preparations obtained from other Salmonella spp. Three major OMPs are presented in the antigen preparation and strong binding of positive sera was detected to all three bands.
authors.affiliation: Institute for Advanced Studies, University of Malaya, Kuala Lumpur.
authors.forename: A
authors.initials: A
authors.lastname: Verdugo-Rodriguez
authors.forename: L H
authors.initials: LH
authors.lastname: Gam
authors.forename: S
authors.initials: S
authors.lastname: Devi
authors.forename: C L
authors.initials: CL
authors.lastname: Koh
authors.forename: S D
authors.initials: SD
authors.lastname: Puthucheary
authors.forename: E
authors.initials: E
authors.lastname: Calva
authors.forename: T
authors.initials: T
authors.lastname: Pang
mesh_terms: D000907:Antibodies, Bacterial / Q000032:analysis*; D001424:Bacterial Infections / Q000276:immunology; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology*; D003429:Cross Reactions; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D004926:Escherichia coli / Q000276:immunology; D005189:False Positive Reactions; D006801:Humans; D015151:Immunoblotting; D007074:Immunoglobulin G / Q000276:immunology; D011237:Predictive Value of Tests; D012485:Salmonella typhi / Q000276:immunology*; D012680:Sensitivity and Specificity; D014435:Typhoid Fever / Q000175:diagnosis / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial; D001425:Bacterial Outer Membrane Proteins; D007074:Immunoglobulin G