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Plasma HIV viral load testing is the preferred means of monitoring antiretroviral treatment response. Dried blood spots (DBSs) hold considerable logistical advantages over EDTA samples, but they more frequently misclassify virological failure and have higher limits of detection (LoD)., Plasma HIV viral load testing is the preferred means of monitoring antiretroviral treatment response. Dried blood spots (DBSs) hold considerable logistical advantages over EDTA samples, but they more frequently misclassify virological failure and have higher limits of detection (LoD). Plasma separation cards (PSCs) may overcome these limitations. Health workers collected EDTA whole blood by venipuncture and 140 μl of finger-prick blood by capillary tube from 53 HIV-infected adults. Capillary blood was immediately transferred to PSCs. Additionally, 432 EDTA samples from HIV-infected adults were spotted onto PSCs and analyzed together with the finger-prick samples. Specificity and sensitivity of PSC with paired EDTA-PSC samples tested on a cobas 6800/8800 system with the cobas HIV-1 test (cobas HIV) was determined. LoD (3rd HIV-1 WHO International Standard) and stability at a range of temperatures and storage durations was determined using cobas HIV and cobas AmpliPrep/cobas TaqMan HIV-1 test v2.0 (CAP/CTM). Of 132 specimens with quantitative values for paired EDTA-PSC samples, the mean log10 difference between samples was 0.05 copies/ml (95% confidence interval [CI], −0.01 to 0.11). The LoD for cobas HIV was 790.2 copies/ml and for CAP/CTM was 737.9 copies/ml. At 1,000 copies/ml, PSC sensitivity was 97.0% (128/132) and specificity was 97.2% (343/353). Results correlated well with those from EDTA samples (Deming R2 = 0.90). PSC results were unaffected by temperature and storage conditions. PSC samples correlate well with plasma viral load and have adequate sensitivity and specificity. The improved performance may be as a result of a reduction in contribution from cell-associated viral nucleic acids. The card provides an alternative sample collection technology to DBSs.

Blood sampling on filter paper has many advantages for the detection of perinatal human immunodeficiency virus (HIV) infection by the polymerase chain reaction (PCR). However, if the method is to be widely used, an assessment of its performance under field conditions is required. To simulate conditions in the field, 50-microliters aliquots of whole blood containing low levels of HIV proviral DNA (4 to 1,024 copies per 100,000 nucleated cells) were spotted onto filter paper; dried; and subjected to heat, humidity, and prolonged storage at room temperature. After exposure, the DNA was recovered and amplified with primers to human leukocyte antigen DQ alpha- and HIV-specific sequences. Treatment at 37 degrees C and 60% humidity for 7 days, storage for 12 weeks at 22 degrees C, and freeze-thawing twice had no adverse effect on PCR reactivity when compared with the results obtained with reference spots stored at -20 degrees C. The lower limits of HIV detection in all tests ranged from 4 to 16 HIV copies per 100,000 cells. Fixation in 70% ethanol improved the amplification of low levels of HIV DNA and reduced biohazard risks. These findings suggest that dried blood spots will provide a powerful new resource for testing for HIV by PCR, especially in remote areas where refrigeration and immediate sample processing are unavailable.