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ObjectivesThe aim of the study was to evaluate the use of dried plasma spots to determine HIV-1 RNA viral loads. MethodsThe viral loads of 30 liquid plasma samples were compared with those of corresponding dried plasma spots on filter paper (DPS-FP) and in tubes (DPS-T), both of which were left for 7 days at 22 1C. Also, 10 liquid plasma samples with detectable viral load were stored at 4, 22 or 37 1C for 7 days and five further liquid plasma samples were air-dried for up to 54 h to assess the effects of temperature and the drying step on HIV-1 viral load. ResultsThe viral loads of the 30 liquid plasma samples correlated significantly with those of the paired dried spots DPS-FP and DPS-T, but with median losses of 0.64 and 0.69 log 10 HIV-1 RNA copies/mL, respectively, and a limit of detection of 3 log 10 copies/mL. The 10 liquid plasma samples stored for 1 week at 37 1C showed a weaker correlation and had a significantly reduced median viral load (-0.92 log 10 ; P 5 0.005) when compared with the viral load of the matched plasma stored at À 80 1C. Most of the loss happened during the drying step. ConclusionsReliable measurement of HIV-1 RNA viral load requires good plasma storage conditions. HIV RNA stability was affected by desiccation and 1 week of storage at 37 1C. However, our findings suggest that liquid plasma can be kept at 4 or 22 1C for a week with no effect on viral load.

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ObjectivesIn resource-limited countries, HIV-1 RNA quantification is usually performed in reference laboratories. Samples from remote areas are transported under suboptimal conditions. Here we evaluated HIV-1 RNA stability in plasma stored at different temperatures for 1 week. MethodsBlood samples collected in ethylenediaminetetraacetic acid (EDTA) and processed within 6 h of collection were tested by HIV-1 RNA quantification using Roche Cobas Ampliprep-Cobas TaqMan s (Roche Diagnostics). The results were compared with matched HIV-1 RNA concentrations determined from plasma stored for 1 week at 4, 22, 30 or 37 1C. ResultsA total of 51 samples were evaluated: 10 stored at 4 1C, 15 at 22 1C, 16 at 30 1C and 10 at 37 1C. Keeping plasma at 4, 22 or 30 1C for 1 week did not affect HIV RNA measurement. Compared with HIV-1 RNA concentrations determined from fresh plasma, the correlation was significant for each of the three temperatures with no RNA decay. In contrast, HIV-1 RNA levels decreased significantly when plasma was stored at 37 1C. The 10 samples submitted at this temperature showed a weaker correlation (r 5 0.84; P 5 0.012) and a significantly reduced median HIV-1 RNA concentration ( À 0.92 log 10 HIV-1 RNA copies/mL; P 5 0.005). ConclusionPlasma can be saved for up to 1 week at 30 1C before shipping to a reference laboratory for HIV-1 RNA quantification.