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Subtype-specific problems with qualitative Amplicor HIV-1 DNA PCR test
M Bøgh1, R Machuca, J Gerstoft
1Retrovirus laboratory, Department of Virology, Statens Serum Institut, Artillerivej 5, DK-2300 Copenhagen S, Denmark. mrb@ssi.dk
Summary
The Amplicor HIV-1 DNA PCR test shows variable sensitivity across different HIV-1 subtypes. Modifying the assay with additional primers improves detection, especially for non-B subtypes.
Area of Science:
- Virology
- Molecular Diagnostics
Background:
- Commercial HIV-1 qualitative DNA PCR tests offer an alternative to antibody tests for early detection and in specific populations.
- The genetic diversity of HIV-1 poses challenges for the sensitivity of PCR-based detection methods across all subtypes.
Purpose of the Study:
- To evaluate the sensitivity of the Amplicor HIV-1 test across seven HIV-1 subtypes.
- To assess the impact of modifying the standard assay with SK145 and SKCC1B primers on detection rates.
Main Methods:
- Testing 126 whole-blood samples from HIV-1 infected individuals representing seven subtypes using the standard Amplicor HIV-1 assay.
- Re-testing samples with a modified assay incorporating an additional primer pair (SK145 and SKCC1B).
Main Results:
- The standard Amplicor HIV-1 test demonstrated an overall sensitivity of 90%, with significant variations by subtype (e.g., 100% for B, D, G; 79% for E; 0% for F).
- Low reactivity was observed in 9% of positive samples, all non-B subtypes.
- The modified assay with additional primers increased sensitivity, converting six of eight previously negative samples to positive, although two remained negative.
Conclusions:
- The Amplicor HIV-1 test exhibits unequal sensitivity for different HIV-1 subtypes, with 10% of tested samples yielding negative results.
- Supplementing the standard assay with SK145/SKCC1B primers is recommended when non-B subtype HIV-1 infection is suspected to enhance diagnostic accuracy.