P5.075 BioPlex ® 2200 HIV Ag-Ab: An Automated Screening Method Providing Discreet Detection of HIV-1 P24, HIV-1 Antibody, and HIV-2 Antibody

Abstract

Background: Develop an automated HIV assay with 4th generation sensitivity that can report antibody and antigen results individually, and distinguish HIV-1 from HIV-2 positives. Methods: The BioPlex 2200 HIV Ag-Ab assay uses multiplex flow immunoassay to detect HIV-1 p24 antigen, HIV-1 antibody (Groups M and O), and HIV-2 antibody in a single reaction vessel using a mixture of four populations of dyed microparticles. Each population is coated with a different HIV antigen or with p24 antibody. Results: for each marker can be reported individually, and antibody-reactive specimens can be typed as HIV-1 or HIV-2. Specimens with similar levels of HIV-1 and HIV-2 antibody reactivity are reported as reactive but undifferentiated. Results: of in-house testing: To assess specificity, 5239 samples of unknown risk were tested resulting in specificity of 99.83%. To assess sensitivity, known positive specimens (209 HIV-1 Group M, 21 HIV-1 Group O, and 177 HIV-2) were tested and all were reactive. All HIV-1 samples (209 Group M and 21 Group O) were correctly identified as HIV-1, and 153 of 177 HIV-2 samples were correctly identified as HIV-2. Of 24 that were undifferentiated, 18 could not be typed by Orgenics Immunocomb®. Among 26 commercial seroconversion panels, BioPlex 2200 detected HIV-1 infection one donation sooner than Abbott Architect Combo HIV (4th generation) in three panels. In one panel, BioPlex 2200 missed one donation positive by Architect. Both tests gave equivalent results for 22 of the 26 panels. Conclusion: The BioPlex 2200 HIV Ag-Ab assay, which is currently in development, is highly sensitive and specific, and can also provide detailed screening results that will assist in identifying specimens from primary infection and HIV-2 positives and guide selection of of supplemental testing.