Correlation between HIV-1 viral load quantification in plasma, dried blood spots, and dried plasma spots using the Roche COBAS Taqman assay

Background: The use of simplified methods for viral load determination could greatly increase access to treatment monitoring of HIV patients in resource-limited countries.

Objective: The aim of the present study was to optimize and evaluate the performance of the Roche COBAS Taqman assay in HIV-RNA quantification from dried blood spots (DBS) and dried plasma spots (DPS).

Study design: EDTA blood samples from 108 HIV-infected women were used to prepare 129 DBS and 76 DPS on Whatman 903 card. DBS and DPS were stored at -20 degrees C. HIV-1 RNA was extracted from DBS/DPS using the MiniMAG system (bioMerieux). Amplification and detection were performed using the Roche COBAS TaqMan assay. Plasma viral load results were used as standard.

Results: There was a high correlation between measures of viral load in plasma and in DBS/DPS (r=0.96 and 0.85 respectively, P<0.001). Overall, viral load values in DBS and DPS tended to be lower than in plasma with mean (SD) differences of 0.32 log(0.22) for DBS and of 0.35 (0.33) for DPS. Detection rates were 96.4% for DBS and 96.1% for DPS in samples with corresponding plasma values >3.0 log copies/ml. Samples with HIV-RNA below 50 copies/ml were correctly identified in 18/19 DBS and in 7/7 DPS.

Conclusions: Both DBS and DPS provided results highly correlated to the plasma values. High detection rate was obtained with both DBS and DPS when HIV-RNA was >3.0 log copies/ml. Our results support the use of DBS/DPS to detect virologic failure in resource-limited settings.