title: Development and validation of an Enzyme Linked Immunosorbent Assay (ELISA) test for the diagnosis of toxoplasmosis in Sri Lanka.
abstract: BACKGROUND
  ELISA is the most widely used form of diagnosis for toxoplasmosis. Several commercial kits are currently used in Sri Lanka. However, these kits are not affordable in resource-limited settings. Objectives Aim of this study was to develop a cost effective in-house ELISA for the detection of Toxoplasma antibody and to estimate the diagnostic accuracy compared to a commercial kit.
  
  
  METHODS
  Vero cell lines were inoculated with tachyzoites and harvested after 2-6 days and sonicated to obtain somatic antigen. The antigen was used as coating material in ELISA to detect antibodies against T. gondii in patient sera. Hundred and three patients' sera were analysed by in-house ELISA and kit ELISA. Optical density (OD) values were analysed statistically. Toxoplasma IgG avidity test was used to determine the chronic and acute phase of infection.
  
  
  RESULTS
  The optimum working dilutions for antigen was 0.846 μg/ml and for serum 1 in 100. The optimal cut-off values for the in-house ELISA within the range 0.85 to 0.98 at which the sensitivity was 95.3% and specificity was 98.3. The OD values of in-house ELISA were compared with OD values of kit ELISA and the results showed strong correlation between the two tests.
  
  
  CONCLUSIONS
  The results of our study demonstrated that our in-house ELISA for detection of T. gondii antibody was as sensitive and specific as the commercial kit used in this study. Thus, the in-house ELISA is a useful, costeffective tool for diagnostic and screening purposes.
authors.affiliation: Department of Parasitology, Faculty of Medicine, University of Peradeniya, Sri Lanka. devikaiddawela@yahoo.com.
authors.forename: D
authors.initials: D
authors.lastname: Iddawela
authors.forename: K
authors.initials: K
authors.lastname: Ehambaram
authors.forename: P V
authors.initials: PV
authors.lastname: Kumarasiri
authors.forename: S
authors.initials: S
authors.lastname: Wijesundera
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000276:immunology*; D000953:Antigens, Protozoan / Q000276:immunology*; D002522:Chlorocebus aethiops; D004797:Enzyme-Linked Immunosorbent Assay; D012680:Sensitivity and Specificity; D012698:Serologic Tests; D013188:Sri Lanka; D014122:Toxoplasma / Q000276:immunology*; D014123:Toxoplasmosis / Q000175:diagnosis* / Q000276:immunology; D014709:Vero Cells
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan