Although several commercial serological kits exist for Toxoplasma serodiagnosis, the unambiguous diagnosis of many clinically important Toxoplasma infections remains problematic. This is particularly true in establishing the timing of infection in pregnant women and in demonstrating reactivation of disease in immunocompromised hosts. The wide tissue tropism and distinct life-cycle stages of toxoplasmosis raise the possibility that the detection of circulating tachyzoite antigens may be of use in these situations. We have developed a series of antigen capture Enzyme Linked Immunosorbent Assays (ELISAs) using a panel of novel monoclonal antibodies (mAbs) directed against T. gondii tachyzoite antigens. Using a pool of these mAbs to capture whole tachyzoite lysate antigen in 'spiked' negative serum, the detection limit of our ELISA was 1--2mug/ml of protein. The sensitivity of this ELISA was 52% (n = 412). We postulated that our low sensitivity was mainly due to circulating immune complexes. This was confirmed by the disappearance of 'spiked' tachyzoite lysate antigen in antibody positive samples followed by the reappearance of antigen upon 12% trichloroacetic acid (TCA) treatment. Furthermore, the use of 12% TCA significantly increased antigen detection (p = 0.00001). Preliminary results suggested that assay sensitivity was 96% (n = 254) while assay specificity was 97% (n = 253). Early reports suggest that Toxoplasma antigen levels in serum are transient. The magnitude and kinetics of antigenemia with the specific Toxoplasma products recognized by our panel of mAbs remain to be determined. This optimized assay can now be used to test sera from otherwise healthy and immunocompromised subjects to determine its clinical utility.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.32998 |
| Date | January 2001 |
| Creators | Grushka, Daniel |
| Contributors | Ward, Brian J. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Microbiology and Immunology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001976371, proquestno: MQ75313, Theses scanned by UMI/ProQuest. |
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