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Published on: September 7, 2018
Dot-immunobinding assay
S Sumi1, A Mathai, V V Radhakrishnan
1Department of Pathology, Sree Chitra Tirunal Institute for Medical Sciences and Technology (SCTIMST), Thiruvananthapuram, 695 011, Kerala, India.
Insights
Dot-immunobinding assay (Dot-Iba) offers a simple, rapid method for diagnosing diseases like tuberculous meningitis. This highly specific assay is ideal for resource-limited settings, showing no false positives.
Area of Science:
- Immunodiagnostics
- Medical laboratory technology
Background:
- The Dot-immunobinding assay (Dot-Iba) is a straightforward and reproducible immunodiagnostic technique.
- It involves immobilizing antibodies or antigens onto nitrocellulose membrane (NCM) discs for sample analysis.
Purpose of the Study:
- To evaluate the efficacy and applicability of the Dot-immunobinding assay (Dot-Iba) as a diagnostic tool.
- To assess its suitability for resource-limited laboratory settings.
Main Methods:
- Antigen or antibody is dotted onto nitrocellulose membrane (NCM) discs.
- Diagnostic samples are incubated on the discs, followed by detection with enzyme-conjugated antiglobulins and substrate.
- Positive results are indicated by a purple-pink colored, insoluble substrate product.
Main Results:
- The Dot-Iba assay demonstrated an overall sensitivity of 60% for tuberculous meningitis diagnosis.
- The assay exhibited high specificity, with no false positive results observed.
- It is particularly effective for diagnosing paucibacillary diseases, including extrapulmonary tuberculosis.
Conclusions:
- Dot-immunobinding assay (Dot-Iba) is a rapid, simple, and highly specific immunoassay.
- It is well-suited for diagnosing paucibacillary diseases and is particularly valuable for laboratories in developing countries with limited resources.
Abstract:
Dot-immunobinding assay (Dot-Iba) is a simple and highly reproducible immunodiagnostic method. Antibody or antigen is dotted directly onto nitrocellulose membrane (NCM) discs. The diagnostic material to be checked can be incubated on this disc. Presence of antigen-antibody complex in NCM discs can be directly demonstrated with enzyme-conjugated antiglobulins and substrate. Development of a purple-pink colored, insoluble substrate product in the NCM will be considered a positive result in the assay. This assay allows the processing of multiple specimens at a time and the entire operational procedures require only 4-6 h. Dot-Iba is rapid, and the technical steps involved in the assay are much simpler than in the other immunoassays such as enzyme-linked immunosorbant assay in detecting circulating antigen and antibody in clinical samples. The Dot-Iba showed an overall sensitivity of 60% for tuberculous meningitis diagnosis and no false positive results were encountered. Hence, this assay is highly specific for the diagnosis of paucibacillary diseases such as extrapulmonary tuberculosis. Dot-Iba is best suited to laboratories in developing world where there are constraints in laboratory resources.
