Background:
HIV-1 viral load in peripheral blood is an important marker for disease prognosis and therapeutic effectiveness. Conventional viral load tests require relatively large volume of plasma and impose stringent conditions on sample collection, processing, storage and shipment. However, the majority of new HIV-1 infections occur in developing regions lacking sufficient resources. The increasing availability of treatment in these regions requires simple and robust methods to facilitate effective patient monitoring. Dried spots represent an attractive option that eliminates many logistical and technical limitations.

Objective:
This study evaluates a viral load method from dried blood spots (DBS) using Abbott RealTime HIV-1 assay.

Method:
50 μL of whole blood or plasma were dispensed onto Whatman 903^® cards and air dried before storage. When tested, whole spots were excised and placed into 1.7 mL Abbott m™ Lysis buffer. After 15 to 120 minute incubation at room temperature, the liquid was transferred to a reaction vessel and processed as a regular sample. Viral RNA was extracted and assembled into RT-PCR reactions by m2000sp™ or manual procedure and was amplified and detected by m2000rt™.

Result:
This method exhibited good linearity between 1,000 and 1,000,000 copies/mL HIV-1 RNA. 100% detection was achieved at 2,000 copies/mL when processing 2 spots per reaction. Viral quantification for DBS samples correlated closely with liquid plasma and dried plasma spot results. HIV-1 RNA on DBS exhibited excellent stability at 25 °C, 2-8 °C and -70 °C.

Conclusion:
Excellent viral load performance was achieved when combining DBS with Abbott m2000™ systems and RealTime HIV-1 assay. Small sample volume, ease of collection and processing, and excellent stability make DBS suitable for resource-limited regions. The ability of Abbott RealTime HIV-1 assay to accurately quantify all HIV-1 variants constitutes a unique advantage for regions with significant HIV-1 genetic diversity.

Implications:
N/A