Abstract
Nucleic acid measurements are used to follow HIV-1 viral load in clinical applications while p24 ELISA is commonly used to monitor HIV-1 replication in research settings. Current ELISA assays are expensive and offer a narrow dynamic measurement range. This report describes a simple, sensitive and inexpensive bead-based assay offering a wide dynamic measurement range. This cytometric bead assay allows the detection of p24 concentrations over 4 orders of magnitude from less than 0.4pg to up to 20,000pgml(-1) in a volume of 50microl and can be combined with other measurements.