Application of Toxocara canis excretory-secretory antigens and IgG subclass antibodies (IgG1-4) in serodiagnostic assays of human toxocariasis.

Abstract

A major problem in the serodiagnosis of human toxocariasis in tropical countries is cross-reaction with antibodies to other helminthic diseases and a lack of sensitivity. The majority of tests currently available use total IgG and, in this study, the use of peroxidase-conjugated anti-human IgG subclass antibodies (IgG1-4) was compared with total IgG for the diagnosis of human toxocariasis by using Toxocara excretory-secretory (TES) antigens in an enzyme-linked immunosorbent assay (ELISA) format. All four IgG subclass antibodies gave approximately 10-fold increases in optical density (OD) values for 50 toxocariasis patients compared to 29 healthy normals; this was significantly greater than the approximate doubling of OD values seen in the total IgG-ELISA format. IgG2 gave by far the greatest sensitivity (values: IgG, 50%; IgG1, 60%; IgG2, 98%; IgG3, 78%; IgG4, 64%). Significant cross-reactivity using all IgG subclasses in the TES ELISA was seen with 141 serum samples from patients with 10 other helminthic infections. However, IgG3 gave the best specificity (values: IgG, 73%; IgG1, 76%; IgG2, 71%; IgG3, 81%; IgG4, 71%). Thus, of the IgG subclass antibodies, IgG2 appeared best and employing this subclass can improve the serodiagnosis of human toxocariasis since it recognises carbohydrate epitopes of TES antigens.

• Authors: Dorn Watthanakulpanich, Huw V Smith, Glyn Hobbs, Anthony J Whalley, David Billington
• Journal: Acta tropica (Acta Trop) Vol. 106 Issue 2 Pg. 90-5 (May 2008) ISSN: 0001-706X [Print] Netherlands
• PMID: 18343348 (Publication Type: Evaluation Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antibodies, Anti-Idiotypic
• Antibodies, Helminth
• Antigens, Helminth
• Immunoglobulin G

Topics

• Animals
• Antibodies, Anti-Idiotypic
• Antibodies, Helminth (blood)
• Antigens, Helminth (isolation & purification)
• Cross Reactions
• Enzyme-Linked Immunosorbent Assay (methods)
• Humans
• Immunoglobulin G
• Sensitivity and Specificity
• Serologic Tests (methods)
• Toxocara canis (chemistry, immunology)
• Toxocariasis (diagnosis)