Rapid Antigen Detection/Immunochromatographic Assay for MTB

Principle: 

This method detects MPT64 antigen specifically produced by the M. tuberculosis complex. It detects MPT64 a mycobacterial protein secreted by the cells during growth.

Testing method:

Immunochromatography is a double-antibody sandwich technique in which:

• An antibody labelled by colloidal particles, such as colloidal gold, reacts with target antigens to form an antigen-antibody complex.

• This complex migrates across a chromatographic carrier such as a filter paper.

•  The complex is captured by a second antibody ready-fixed in the middle of the chromatographic carrier.

If the target antigens are present in the test specimen, a colour reaction caused by the gold colloidal particles is observed at the site on the chromatographic carrier where the second antibody is fixed, and the specimen is interpreted as positive.

This kit employs the colloidal gold-labelled MPT64 monoclonal (mouse) antibody in the main reaction system. The results are visually identified as a specific antigen-antibody reaction between the monoclonal antibody and MPT64 antigens secreted by the isolate. 

However, if the growth of the M. tuberculosis complex is slight and the MPT64 concentration in the test specimen is below the detection limit, the complex may not be detected.

Resource

Mycobacteriology Laboratory Manual

Assessment