|Values are valid only on day of printing.|
Specimens are first screened by the Genetic Systems HBsAg 3.0 EIA. All reactive results are confirmed by the Genetic Systems HBsAg Confirmatory Assay 3.0 (HBsAg Neutralization) at an additional charge.
Wells of a microwell strip plate that are coated with mouse monoclonal antibody to hepatitis B surface antigen (HBsAg) are incubated with patient serum appropriate controls and mouse monoclonal anti-hepatitis B surface (anti-HBs) peroxidase conjugate. HBsAg, if present, is bound to the solid-phase antibody and simultaneously bound by the anti-HBs conjugate. After aspiration and washing, working chromogen solution is added to the wells. After incubation, a blue or blue-green color develops in proportion to the amount of HBsAg bound to the bead.
The enzyme reaction is stopped by the addition of acid resulting in a color change to yellow. The absorbance values of controls and specimens are determined using a spectrophotometer with wavelength set at 450 nm. Specimens giving absorbance values equal to or greater than the absorbance value of the negative control mean plus a factor are considered initially reactive for HBsAg. Those giving absorbance values less than the negative control mean plus a factor are considered negative.(Package insert: Genetic Systems HBsAg 3.0 EIA. Bio-Rad Laboratories, Redman, WA)
The Genetic Systems HBsAg Confirmatory Assay 3.0 uses the principle of specific antibody neutralization to confirm the presence of HBsAg. The confirmatory reagent (human antibody to HBsAg) is incubated with the specimen in solution. If HBsAg is present in the specimen, it will be bound by the confirmatory reagent. The treated specimen is reassayed using the Genetic Systems HBsAg 3.0 EIA kit. The neutralized HBsAg is subsequently blocked from binding to the antibody-coated wells. This results in a reduction of signal when compared to the nonneutralized specimen in which negative control is used in place of confirmatory reagent. By definition, a specimen is confirmed as positive if the reduction in signal of the neutralized specimen is at least 50% and the nonneutralized control generates a signal greater than or equal to the assay cutoff.(Package insert: Genetic Systems HBsAg Confirmatory Assay 3.0. Bio-Rad Laboratories, Redman, WA)
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