Validation of a Low-Volume (100 μL) Plasma Protocol for HIV-1 RNA Quantification Using the Hologic Aptima HIV-1 Quant...

Pediatric HIV-1 viral load monitoring is often limited by the small blood volumes that can be safely obtained from infants and young children. Standard assays typically require 0.5 to 0.7 mL of plasma, which can pose challenges in these settings. This study evaluated a modified low-volume protocol using 100 μL of plasma, diluted for use with the Hologic Aptima HIV-1 Quant Dx assay, to determine whether performance was equivalent to the standard 700 μL protocol. An analytical validation was conducted by using de-identified EDTA plasma samples spanning a wide range of HIV-1 RNA concentrations. Each specimen was tested by using both protocols on the Panther system. Agreement between methods was assessed by using log₁₀ differences, correlation analysis, and Bland-Altman analysis; within-run and between-run precision was evaluated by using replicate testing of negative, low-positive, and high-positive samples. The 100 μL protocol displayed excellent concordance with the standard method, with a mean log₁₀ difference of approximately 0.00 and a maximum difference of 0.12 log₁₀ copies/mL. No false-positive or false-negative results were observed among 30 fully suppressed samples. Precision analyses showed minimal variability, with all results within predefined acceptability criteria. These findings indicate that the low-volume Aptima protocol provides accurate and reliable HIV-1 RNA quantification and can expand access to viral load testing in pediatric patients and other clinical settings in which plasma volume is limited.