Plasma virion reverse transcriptase activity and heat dissociation-boosted p24 assay for HIV load in Burkina Faso, West Africa

Background: In resource-limited settings, the requirement for inexpensive, easy-to-perform viral load monitoring has increased with greater antiretroviral drug availability.

Objectives: To evaluate feasibility, in Burkina Faso, of a simple assay for plasma HIV reverse transcriptase (RT) activity quantification compared to heat dissociation-boosted (HDB) p24 antigen and RNA-based quantifications in plasma samples from HIV-infected patients.

Methods: Plasma viraemia was quantified by RT activity, HDB-p24 and RNA copies in 84 samples from 70 HIV-1 group M-infected patients (82% non-B subtype, 93% treatment naive), including serial samples from nine patients.

Results: RT activity detected 86% of plasma samples containing measurable RNA copies; corresponding to 0, 93 and 100% of samples with 1.7-4.0 log₁₀, 4.1-4.8 log₁₀ and 4.9-6.7 log₁₀ RNA copies/ml, respectively. HDB-p24 detected 77% of plasma samples containing measurable RNA copies; corresponding to 27, 80 and 86% of samples with 1.7-4.0 log₁₀, 4.1-4.8 log₁₀ and 4.9-6.7 log₁₀ RNA copies/ml, respectively. Measurement error based on one-way analysis of variance between RT activity and HDB-p24 values with RNA copies showed good agreement with RT activity (ME, <10%), however poorer agreement was obtained with HDB-p24 values (ME, >10%). Patient follow up showed a similar pattern of viraemia with RNA and RT activity assays.

Conclusion: Field trials in Burkina Faso support the practical use of plasma RT activity assay as an affordable alternative for HIV viral load determination in regions where RNA detection remains difficult to perform. HDB-p24 use requires further evaluation before being considered as an alternative method in African HIV-infected patient follow up.