Background The Hologic Aptima HIV-1 Quant Assay that is currently available on the Panther system is FDA-cleared for plasma viral load monitoring. We compared to other assays for use with dried blood spots (DBS) and for early infant diagnosis (EID) using plasma and DBS.

Methods Spiked dilution panels of plasma and DBS were made using negative donor blood and subtype B and subtype C HIV-1 stocks. Patient samples included plasma from HIV-1-infected adults, plasma from HIV-1-infected infants and exposed uninfected infants, and DBS from infected adults. Samples were run on Aptima Quant and either Abbott RealTime HIV-1 Quant assay or Hologic Aptima HIV-1 Qual assay.

Results Aptima Quant and Abbott Quant were comparable: the 95% limit of detection was 42cp/ml for Aptima Quant and 91cp/ml for Abbott Quant. EID comparisons showed that Aptima Quant and Qual had 100% sensitivity and 98.9% specificity with overall agreement between the assays of 98.4%. Aptima Qual had a slightly lower limit of detection (95% limit of detection was 27cp/ml for Aptima Qual and 65 cp/ml for Aptima Quant). With spiked DBS, all 16 DBS with >30cp/ml on Aptima Quant were detected on Aptima Qual, 10/12 (83%) with ‘<30 detected’ on Aptima Quant were detected on Aptima Qual, and 2 of 14 (14.3%) with ‘not detected’ on Aptima Quant were detected on Aptima Qual. Among 200 DBS from infected adults, overall agreement between the Aptima Quant and Aptima Qual was 90% when ‘<30 detected’ was counted at positive. 13 DBS from uninfected adults were negative on both assays.

Conclusion The Hologic Aptima HIV-1 Quant assay performed similarly for viral load and EID on both plasma and DBS samples. Our data suggest the ‘<30 detected’ result could be used as the indeterminate range for Aptima Quant using DBS, as recommended by the new WHO guidelines.

Disclosure No significant relationships.