AEGiS-11IAC: Sensitive HIV antigen assay detecting HIV-1 group M, HIV-1 group O and HIV-2 core proteins.

11th International AIDS Conference

Vancouver, British Columbia — July 7-12, 1996

Sensitive HIV antigen assay detecting HIV-1 group M, HIV-1 group O and HIV-2 core proteins.

Int Conf AIDS 1996 Jul 7-12; 11:8 (abstract no. Mo.A.162)
Louwagie J, Garrett PE, Mertens G, Van Geel A, Pollet D, van den Abeele A, Saman E; Innogenetics, Zwijdrecht, Belgium. Fax: 32 3 252 37 98.

OBJECTIVES: To study the sensitivity and specificity of a newly developed antigen assay for the broad spectrum detection of HIV capsid antigens in human serum and to validate the confirmatory and immune complex dissociation reagents.

METHODS: The INNOTEST HIV Antigen mAb is a sandwich ELISA, based on a human immunoglobulin preparation as the capturing antibody (Ab) and two biotinylated monoclonals as detector antibodies. The bound monoclonals are revealed using streptavidin-peroxidase conjugate and TMB as the chromogen. The cutoff is defined as the mean of the negative controls plus 50 mOD. Confirmation is considered positive when the signal is decreased by at least 50% upon addition of the confirmatory antibody.

RESULTS: The specificity of the assay was estimated at 99.8% with sera from blood donors. In supernatants from cells infected with HIV-1 group M, HIV-1 group O and HIV-2 viruses, the antigen could be quantified with a detection limit for HIV-1 of up to 4 pg/ml, relative to the Pasteur p24 standard. When spiked in HIV-negative human serum, the sensitivity was 11 pg/ml. All samples could be confirmed by the confirmatory assay. Each of the 18 HIV antigen positive and both HIV antigen negative samples in the Boston Biomedica (BBI) mixed titre panel (PRA201) were correctly identified. Application of the immune complex dissociating reagent resulted in an important increase in signal to noise ratio for 5 samples of the same BBI panel. In another BBI panel of 26 antigen positive seroconversions, the INNOTEST HIV Antigen was able to detect HIV antigen earlier (2 cases) or at least equally early (24 cases) as 4 other commercial antigen dosage assays, whereas and continuing antigenemia after seroconversion was detected later in 9 out of the 26 cases. When compared with nucleic acid amplification methods, 23 out of 26 BBI antigen positive seroconversion panels were found positive at the same time point and the three remaining were positive in the subsequent sample.

CONCLUSION: These results indicate that the monoclonal antibody based INNOTEST HIV Antigen detects a broad spectrum of HIV antigens and combines an excellent sensitivity and specificity in serum samples with an efficient immune complex dissociation procedure.

Keywords: AEGIS, HIV-2, HIV Antigens, HIV-1, HIV Infections, Viral Core Proteins, Enzyme-Linked Immunosorbent Assay, Blood Donors, Antigen-Antibody Complex, Sensitivity and Specificity, Antibodies, Monoclonal, Antiviral Agents, Capsid, Boston, Human, virology, ICA11

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MoA162