|Values are valid only on day of printing.|
Specimens are first tested by the VITROS HBsAg assay. Per assay manufacturer's recommendation, all hepatitis B surface antigen (HBsAg)-reactive specimens (signal-to-cutoff ratios > or =1.00) in prenatal screening should be confirmed by the VITROS HBsAg Confirmatory assay.
This immunometric technique involves the simultaneous reaction of HBsAg in the sample with mouse monoclonal anti-hepatitis B surface (anti-HBs) antibody coated onto the wells, and a horseradish peroxidase (HRP)-labeled mouse monoclonal anti-HBs antibody in the conjugate. Unbound conjugate is removed by washing. A reagent containing luminogenic substrates (a luminol derivative and a peracid salt) and an electron transfer agent is added to the wells. The HRP in the bound conjugate catalyzes the oxidation of the luminol derivative, producing light. The electron transfer agent increases the level and duration of the light produced. The light signals are read by the VITROS ECi System. The amount of HRP conjugate bound is indicative of the level of HBsAg present in the sample.(Package insert: VITROS HBsAg assay, number J03798, version 1.0; Ortho-Clinical Diagnostics, Inc, Rochester, NY)
The VITROS HBsAg Confirmatory Kit uses the principle of specific antibody neutralization to confirm the presence of HBsAg. The sample is tested twice: 1 aliquot is incubated with a neutralizing reagent containing high-titer anti-HBs (the confirmatory antibody); the second aliquot is incubated with a nonneutralizing control reagent (the sample Diluent). The confirmatory antibody binds to HBsAg in the sample, inhibiting its reaction in the VITROS HBsAg assay. This leads to a reduced result compared to that for the nonneutralized control sample.(Package insert: VITROS HBsAg Confirmation assay, number J10583, version 1.0; Ortho-Clinical Diagnostics, Inc, Rochester, NY)
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