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Recombinant-based competitive anti-HIV assay: solution of some operating problems
1North London Blood Transfusion Centre, Colindale, England, UK.
Medical Laboratory Sciences
|January 1, 1990
Summary
Recombinant HIV assays can show false negatives with plasma samples due to a
Area of Science:
- Immunology
- Virology
- Clinical Chemistry
Background:
- The Wellcozyme anti-HIV recombinant assay is a diagnostic tool for detecting HIV antibodies.
- Variations in sample matrix (serum vs. plasma) can impact assay performance.
- Understanding these variations is crucial for accurate HIV diagnosis.
Purpose of the Study:
- To investigate the discrepancy in anti-HIV antibody detection between serum and plasma samples using the Wellcozyme assay.
- To identify factors contributing to the observed 'plasma effect' and develop mitigation strategies.
Main Methods:
- Comparison of anti-HIV antibody reactivity between matched serum and plasma samples.
- Testing plasma samples after dilution in negative serum or kaolin treatment.
- Evaluating the effect of incubator temperature on assay results.
- Assessing the performance of a different anti-HIV test (cell-derived antigen) for comparison.
Main Results:
- A strongly reactive anti-HIV result in serum was not reproducible with the corresponding plasma sample.
- Dilution in negative serum or kaolin treatment of plasma restored reactivity.
- Reducing incubator temperature minimized the 'plasma effect'.
- Initial issues with haemolysed samples and non-standard anticoagulant concentrations were noted.
- The cell-derived antigen test did not exhibit the same plasma-related issues.
Conclusions:
- A 'plasma effect' can interfere with anti-HIV antibody detection using the Wellcozyme recombinant assay.
- Sample preparation (dilution, kaolin treatment) and temperature control can overcome this interference.
- New diagnostic technologies may present unforeseen challenges that require optimization for reliable results.