Correlation between Human Immunodeficiency Virus Type 1 (HIV-1) RNA Measurements Obtained with Dried Blood Spots and Those Obtained with Plasma by Use of Nuclisens EasyQ HIV-1 and Abbott RealTime HIV Load Tests

Abstract

The plasma human immunodeficiency virus (HIV) RNA load is used in the clinical routine for the monitoring of HIV infection and the patient's response to antiretroviral therapy. Other body fluids or dried blood spots (DBS) can be used, however, to assess the level of viremia. The use of DBS may be especially helpful for the monitoring of HIV-infected patients in resource-poor settings, where access to adequate laboratory facilities is often difficult. However, the correlation between the HIV RNA levels in plasma and those in DBSs has not been well established. Paired plasma and DBS samples obtained from HIV type 1 (HIV-1)-infected patients were tested for HIV RNA copy numbers by using two different commercial assays, the Nuclisens EasyQ HIV-1 (version 1.1) test (the Nuclisens test; Biomerieux) and the m2000rt RealTime HIV test (the m2000rt test; Abbott). Nucleic acid extraction was performed manually by using either the Nuclisens isolation kit (which uses the Boom methodology) or the m2000rt sample preparation kit (an iron particle-based method). A total of 103 paired plasma and DBS samples were tested. Viral load results were obtained for 97 (94.2%) samples with the Nuclisens isolation kit and 81 (78.6%) samples with the m2000rt kit. The overall correlation between the RNA loads in plasma and DBS was good, although better results were obtained by the Nuclisens test (R 2 ‫؍‬ 0.87, P < 0.001) than by the m2000rt test (R 2 ‫؍‬ 0.70, P < 0.001). While the specificities were excellent and similar for both the Nuclisens and the m2000rt tests (97.1% and 100%, respectively), the sensitivity was greater by the Nuclisens test than by the m2000rt test (75.8% and 56.6%, respectively). Overall, the viral loads in DBS tended to be lower than those in plasma, with mean differences of 0.3 log unit (standard deviation, 0.5 log unit) and 0.76 log unit (standard deviation, 0.8 log unit) for the Nuclisens and the m2000rt tests, respectively. The levels of agreement between the measurements in plasma and DBS were assessed by using the Bland-Altman plot for each assay. The Nuclisens test gave results within its defined limits (؊0.65 to 1.26) for 95.9% of the samples, while the m2000rt test gave results within its limits (؊0.83 to 2.33) for 100% of the samples. In summary, the HIV-1 load can accurately be quantified by testing DBS by either the Nuclisens or the m2000rt test, although the Nuclisens test may outperform the m2000rt test when nucleic acids are extracted manually.

Comparison of HIV-1 RNA Measurements Obtained by Using Plasma and Dried Blood Spots in the Automated Abbott Real-Time Viral Load Assay

“…However, automation of the procedure may improve agreement between the results obtained testing DBS and plasma due to the reduced human intervention, lower risk of cross contamination, and more rapid turnaround time. In our current study, the correlation between the VL measurements in plasma and DBS was satisfactory and was superior to the results obtained previously using manual RNA nucleic acid isolation (11).…”

“…A previous study showed that manual RNA nucleic acid isolation using the Abbott mSample preparation system resulted in good correlation compared with automatic procedures (11). However, automation of the procedure may improve agreement between the results obtained testing DBS and plasma due to the reduced human intervention, lower risk of cross contamination, and more rapid turnaround time.…”

“…Although the correlation with plasma values was acceptable, the sensitivity was significantly lower on DBS (ϳ3.5 log copies) (11). Improvements in the detection limit (similar to plasma values of ϳ400 copies/ml) are important for early recognition of virological failure in patients on antiretroviral treatment.…”

Non-AIDS Morbidity among HIV Patients

“…However, the sensitivity of dried blood spots for viral load determination at this threshold may be reduced (210,211). Programmes relying on dried blood spot technology for viral load assessment may therefore consider retaining the higher threshold (3000-5000 copies/ml) until sensitivity at lower thresholds is established (212-214).…”

Micro- and Nanotechnology for HIV/AIDS Diagnostics in Resource-Limited Settings

“…Multiple studies have also explored the possibility of transporting dried blood or plasma specimens from more primitive sites to a capable laboratory as a global health solution for plasma viral load testing, though this does not address the ultimate need for a rapid, PoC test [21]- [24]. Progress toward viral load in resource-limited settings has emerged in the form of assays for other biomolecular components of HIV, including the structural capsid protein p24 and the enzyme reverse transcriptase (RT), platforms aimed at the miniaturization of the amplification and/or detection aspects of nucleic acid quantification, and isolation of whole viruses from blood samples as a processing step toward direct particle counting.…”