Multicenter evaluation of use of dried blood and plasma spot specimens in quantitative assays for human immunodeficiency virus RNA: measurement, precision, and RNA stability

Abstract

Eleven laboratories evaluated the use of dried blood and plasma spots for quantitation of human immunodeficiency virus (HIV) RNA by two commercially available RNA assays, the Roche Amplicor HIV-1 Monitor and the bioMerieux NucliSens HIV-1 QT assays. The recovery of HIV RNA was linear over a dynamic range extending from 4,000 to 500,000 HIV type 1 RNA copies/ml. The Monitor assay appeared to have a broader dynamic range and seemed more sensitive at lower concentrations. However, the NucliSens assay gave more consistent results and could be performed without modification of the kit. HIV RNA was stable in dried whole blood or plasma stored at room temperature or at -70 degrees C for up to 1 year. Dried blood and dried plasma spots can be used as an easy and inexpensive means for the collection and storage of specimens under field conditions for the diagnosis of HIV infection and the monitoring of antiretroviral therapy.

FIG. 1.

Log₁₀ estimated HIV RNA concentrations plotted against log₁₀ nominal HIV RNA concentrations for the NucliSens and Monitor assays. Panel 1 specimens were tested on two different occasions (round A and round B). The horizontal line represents the median estimated concentration at each nominal concentration.

FIG. 2.

Results for panel 2 showing the median log₁₀ hematocrit-adjusted (Hct Adj.) estimated HIV RNA concentrations in DBSs in each laboratory plotted against the median log₁₀ estimated HIV RNA concentrations in plasma for all laboratories in which the same kit was used. The dotted line represents the line of equivalence.

FIG. 3.

Median log estimated RNA concentrations for DBSs versus time (weeks) in storage. The effect of storage at room temperature (left) or at −70°C (right) for DBSs was tested by the NucliSens assay. Each symbol is the median for one patient at a given time point in a given laboratory. The line segments join the medians for data from all laboratories combined.