Evaluation of a fully automated, fourth generation immunoassay for the simultaneous detection of HIV antigen and antibody

We evaluated a novel, fully automated assay capable of simultaneously detecting early and established infection by HIV-1 and HIV-2. The combination immunoassay detects antibodies to HIV-1 and HIV-2 as well as p24 antigen in human serum or plasma. The early detection of HIV infection allows HIV therapy to be initiated in a clinically relevant time frame. The VIDAS HIV DUO Ultra (bioMerieux) is an enzyme-linked fluorescent immunoassay that is performed on the automated VIDAS instrument. Following addition of sample, the instrument proceeds independently to perform all maneuvers and provides a printout of results. The VIDAS HIV DUO Ultra was challenged with 2846 samples that included 74 members of 10 HIV seroconversion panels, nine members of a worldwide clade panel, 503 consecutively-collected samples from individuals seeking care at the University of Maryland Medical System, 1010 blood donors, 1141 samples from patients in a high HIV incidence population in Trinidad, 83 samples from an STD clinic in the Bahamas, 10 confirmed HIV-1 Group O samples, and 16 confirmed HIV-2 samples from Cote d' Ivoire. Reference testing was performed using US FDA-licensed antibody screening and confirmatory assays and antigen tests. The Roche Diagnostics Amplicor HIV-1 Monitor Test was utilized to assist in resolving discordant samples. The assay demonstrated 100% sensitivity and 99.4% specificity overall, with a 99.7% specificity in low risk individuals. The analytical sensitivity of the test for detecting early infection, as assessed by seroconversion panels and p24 antigen in the samples from different HIV-1 clades, was equivalent to or better than assays used in the characterization of these panels. We conclude that the VIDAS HIV DUO Ultra performed excellently, offers several advantages over conventional HIV testing including time and cost savings, and is more sensitive than HIV antibody assays for detecting early infection so that intervention therapy can be initiated quickly.