Method Description

The Elecsys HIV DUO assay is based on the sandwich principle and performed using an electrochemiluminescence immunoassay on the automated cobas e 801 immunochemistry analyzer. HIV-1 p24 antigen (Ag) present in patient’s sample first reacts with biotinylated monoclonal anti-p24 antibodies and ruthenylated monoclonal anti-p24 antibodies, to form a sandwich complex. In a separate reaction vessel, HIV-1 and HIV-2 antibodies (Ab) present in the same sample react with biotinylated HIV-specific recombinant antigens/peptides and ruthenylated HIV-specific recombinant antigens/peptides, to form a sandwich complex. After addition of streptavidin-coated microparticles (solid phase) to each reaction vessel, the complexes bind to the solid phase via interaction of biotin and streptavidin. The reaction mixtures are then each aspirated into the measuring cell where the microparticles are magnetically captured onto the surface of the electrode. Unbound substances are then washed away, and voltage is applied to the electrode which induces chemiluminescent emissions that are measured by a photomultiplier. Test result is determined by comparing the electrochemiluminescence signal generated from the reactions to the cutoff index (COI) values set from reagent lot-specific assay calibration for the corresponding HIV-1 p24 Ag and HIV Ab.(Package insert: Elecsys HIV DUO. Roche Diagnostics; v1.0, 12/2020)