Evaluation of sensitivity and specificity of six combined P24 antigen and HIV antibody screening assays

Abstract number: 902_p1644

Ly T.D.


Early detection of human immunodeficiency virus (HIV) infection is critical for clinical diagnosis and safety of blood products.


To evaluate performance of six HIV-combined antigen–antibody (Ag/Ab) assays: AxSYM HIV Combo, Enzygnost HIV Integral, Genscreen Ag/Ab Plus, Murex HIV Ag/Ab Combo, VIDAS HIV DUO and Vironostika HIV Uniform II Ag/Ab. Two-third generation antibody-only assays (Genscreen HIV 1/2 v.2 and Ortho HIV 1/2 antibody Capture) were also evaluated.


The specimens for sensitivity evaluation included: 25 seroconversion panels, HIV-1 antigen panel of 31 cell-culture derived, diverse group M subtypes and group O (each isolate tested at 2, 5, 10, 25 pg/mL of P24 Ag) and 669 of HIV-1 or HIV-2 samples collected from various areas of the word. For specificity, 1005 unselected HIV negative samples collected from four French laboratories were used.


For the detection of P24 Ag, Murex and AxSYM showed the best limit detection of P24 Ag (6–8 pg/mL) irrespective of train, VIDAS DUO could detect 12 pg/mL except for some subtypes C strains and the limit detection of Genscreen Plus was 20 pg/mL except subtype F and group O. The Vironostika and Enzygnost that did not detect any of the HIV strains at 25 pg P24/mL. Of 25 seroconversion panels, AxSYM and Murex detected the first positive bleed in 23 and 21 panels respectively, whereas VIDAS DUO, Genscreen Plus, Enzygnost, Vironostika, Genscreen v.2 and Ortho detected the first positive bleed in 12, 10, 6, 6, 5 and 4 panels, respectively. The 553 HIV-1 group M, 6 HIV-1 group O and 110 HIV-2 positive samples were detected by all assays except Genscreen HIV 1/2 v.2 which missed 1 group O, VIDAS DUO missed 1 subtype F, Enzygnost missed 1 subtype C and Genscreen Plus missed 1 subtype B. The specificity for assays were: Ortho 100%; Genscreen Ag/Ab Plus 99.9%; AxSYM Combo 99.8%; Enzygnost 99.7%; Vironostika and Murex Combo 99.6%; VIDAS DUO 99.5% and Genscreen HIV v.2 99.4%.


These results show that the Ag/Ab HIV combined assays present better performance when compared with third generation antibody assays, however, there are significant sensitivity and specificity differences among combination assays.


Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Location: Oxford, UK
Presentation type:
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