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Test Principle

The TB Antibody Rapid Test device is a lateral flow chromatographic immunoassay based on the principle of the double antigen–sandwich technique. The test cassette consists of: 1) a burgundy colored conjugate pad containing M.TB antigens conjugated with colloid gold (M.TB conjugates) and rabbit IgG‐gold conjugates, 2) a nitrocellulose membrane strip containing a test band (T band) and a control band (C band). The T band is pre‐coated with non‐conjugated M.TB antigens, and the C band is pre‐coated with goat anti‐rabbit IgG.

When an adequate volume of test specimen is dispensed into the sample well of the cassette, the specimen migrates by capillary action across the cassette. The antibodies: either the IgG, the IgM to M. TB if present in the specimen will bind to the M.TB conjugates. The immunocomplex is then captured on the membrane by the pre‐coated M.TB antigens, forming a burgundy colored T band, indicating a M.TB Ab positive test result.

Absence of the T band suggests a negative result. The test contains an internal control (C band) which should exhibit a burgundy colored band of the immunocomplex of goat anti‐rabbit IgG/rabbit IgG‐gold conjugate regardless the presence of any antibodies to M.TB. Otherwise, the test result is invalid and the specimen must be retested with another device.

Assay Procedure

1. Bring the specimen and test components to room temperature. Place the test device on a clean, flat surface.

2. Be sure to label the device with specimen’s ID number.

3. Fill the plastic dropper with the specimen. Holding the dropper vertically, dispense 2 drops (about 80 µL) of specimen into the sample well making sure that there are no air bubbles. Then add 1 drop of buffer into the sample well. Set up timer.

4. Results can be read in 10 minutes. Positive results can be visible in as short as 1 minute. Don’t read result after 10 minutes. To avoid confusion, discard the test device after interpreting the result.