HIV Antigen and Antibody Screen

The Qualitative detection of HIV-1 p24 antigen or HIV-1/HIV-2 antibodies in the sera using the FDA approved ARCHITECT HIV Ag/Ab Combo, two-step chemiluminescent microparticle immunoassay (CMIA).

In the first step, sample, assay diluent, and HIV-1/HIV-2 antigen and HIV-1 p24 mouse monoclonal antibody coated particles coated paramagnetic microparticles are combined.

In the second step, bound HIV-1 p24 antigen and HIV-1/HIV-2 antibodies bind the acridinium -labeled conjugates. Then pre-trigger and trigger solutions are added to the reaction mixture. The resulting chemiluminescent reaction is measured as relative light units (RLUs).

The presence or absence of HIV-1 p24 antigen or HIV-1/HIV-2 antibodies in the sample is determined by comparing the chemiluminescent signal in the reaction to the cutoff signal determined from an ARCHITECT HIV Ag/Ab Combo calibration. Specimens with signal to cutoff (S/CO) values ≥ 1.00 are considered reactive for HIV-1 p24 antigen or HIV-1/HIV-2 antibodies. Specimens with S/CO < 1.00 are considered nonreactive.

Reactive samples are confirmed using the BioRad Geenius HIV 1/2 Supplemental Assay, an immunochromatographic assay for the confirmation and differentiation of individual antibodies to HIV-1 and HIV-2.

Preferred: 7 mL blood in PEARL TOP [ (EDTA) (PPT)] tube

Also Acceptable: 7 mL blood LAVENDER TOP (EDTA) tube

Note: Frozen plasma is also acceptable

Blood: Specimens may be stored on or off the clot, red blood cells, or separator gel for up to 48 hours at room temperature (15-30°C) or up to 7 days at 2-8°C. If testing will be delayed more than 2 days for specimens stored at room temperature or more than 7 days for specimens stored at 2-8°C, remove serum from the clot, red blood cells, or separator gel and store at -20°C or colder. Avoid more than three freeze/thaw cycles.

Outside Laboratories: Specimens may be stored on or off the clot, red blood cells, or separator gel for up to 2 days at room temperature (15-30°C) or up to 7 days at 2-8°C. If testing will be delayed more than 2 days for specimens stored at room temperature or more than 7 days for specimens stored at 2-8°C, remove serum from the clot, red blood cells, or separator gel and store at -20°C or colder. Avoid more than three freeze/thaw cycles.

Unacceptable samples: Cord blood, neonatal specimens, cadaver specimens, heat-inactivated specimens, or body fluids such as saliva, urine, amniotic fluid, or pleural fluid. Specimens with obvious microbial contamination or are grossly hemolyzed.

Note: Except for rapid HIV testing (RHIVNW, PESHIV, and HIVRWC), specimens for this assay should not be used for any other tests. In cases of employee exposure or other unusual circumstances where obtaining a dedicated sample is not possible, please contact the Clinical Virology Lab at 206 685-8037.