Dried blood spots versus plasma for the quantitation of HIV-1 RNA using a real-Time PCR, m2000rt assay

Abstract

High costs and stringent requirements for storage and transport of plasma, often prohibit the availability of HIV viral load quantification in resource-limited settings. Dried blood spots (DBS) represent a better method of specimen collection that removes many of these logistical and technical limitations. The present study aimed to assess the performance of the Abbott m2000rt assay for quantitation of HIV-1 RNA in DBS specimens using plasma as a "gold standard" for comparison. One hundred paired DBS and plasma specimens were collected from patients infected with HIV, who were 18 years and older during routine visits to a private tertiary-care clinic in Chennai, India. HIV-1 RNA was extracted manually and then detected using the m2000rt assay. The mean plasma and DBS viral loads were 4.27 (95% CI: 2.65, 5.88) and 4.14 (95% CI: 1.96, 6.32) log copies/mL, respectively. The overall sensitivity of DBS reached 95%; with sensitivities of 62%, 88% and 100% when stratified by viral load ranges of ≤1000, 1000-3000 and >3000 copies/mL, respectively. An over quantitation of the viral load with DBS was observed in pairs with plasma viral load<3000 copies/mL [d=-0.3 log copies/mL (ranging from -0.1 to 0.6 log copies/mL)]. The study showed a strong concordance in RNA levels between plasma and DBS. The use of DBS specimens should be considered for HIV monitoring and for detection of virologic failure in resource-limited settings.