Ultrasensitive quantitative HIV-1 p24 antigen assay adapted to dried plasma spots to improve treatment monitoring in low-resource settings

Background: Our group has previously developed a quantitative and Ultrasensitive HIV-1 p24 antigen assay that is inexpensive, easy-to-perform, and can be carried out in low-resource settings. Since antiretroviral therapies are becoming more accessible in resource-constrained countries, methods to assess HIV-1 viraemia are urgently needed to achieve a high standard of care in HIV-1 management. Objectives: To adapt our quantitative assay to dried plasma spots (DPS), in order to further simplify this test and make it more accessible to resource-constrained countries. Study design: DPS from 47 HIV-seropositive, treated or untreated adult individuals and 30 healthy individuals were examined. Results: A specificity of 100% was observed when p24 antigen was measured using DPS, and no differences of p24 concentration could be seen between DPS and venous plasma. The correlation between DPS and venous plasma p24 was excellent (R = 0.93, CI95% = 0.88-0.96 p < 0.0001). Similarly, p24 antigen concentrations using DPS were well correlated with RNA viral load (R = 0.53, CI95% = 0.27-0.72, p = 0.0002). Conclusions: This quantitative p24 antigen test has similar sensitivity and specificity using DPS and venous plasma, and has the potential to improve health care delivery to HIV-affected individuals in resource-constrained countries. (C) 2005 Elsevier B.V. All rights reserved.