Viral load (VL) is a critical marker for monitoring HIV disease progression and response to antiretroviral therapy. In resource-constrained settings, there is a need for a simple and inexpensive assay to monitor infected adults and children.
We compared versions 2 and 3 of the ExaVir™ Load assay, Cavidi AB (HIV RT) with the Roche, COBAS® Amplicor® HIV-1 Monitor assay (HIV RNA) for quantifying HIV VL.
The HIV RT version 2 assay showed good sensitivity with detection in 94% of samples with HIV RNA >1000 copies/ml. Adult samples were tested using HIV RT version 2 (n=35) and version 3 (n=23) assays with plasma volumes of 1ml (recommended), 0.5ml and 0.25ml in comparison with HIV RNA. The HIV RT and HIV RNA assay results were comparable when tested using different volumes. Comparison of results from pediatric samples (n=27), tested using 1ml and a smaller volume by HIV RT version 2 were not significantly different.
The HIV RT assay was comparable to the HIV RNA assay with sensitivity approaching that of RT-PCR. Smaller volumes than the recommended 1ml can be used, improving utility of this assay for pediatric monitoring.
Keywords: Monitoring HIV infection, HIV reverse transcriptase, viral load, resource constrained countries, pediatric testing