Immunosorbent Agglutination Assay
The Immunosorbent Agglutination Assay (ISAGA) is a serological detection test for antibodies against Toxoplasma .
It is used to detect specific antibodies in a patient's serum . The test is carried out in round-bottom microtiter plates , on the bottom of which there are immobilized antibodies. The type of immobilized antibodies used determines what type of antibodies the patient's serum is examined for. These are available for IgA and IgM .
Test procedure using the example of IgM detection
- Immobilized anti-human IgM antibodies (blue in the picture) capture all IgM antibodies (red in the picture) from the sample.
- Repeated washing to remove residual plasma.
- The reaction vessel is covered with Toxoplasma antigens (green in the picture).
- evaluation
- The test reads negative if the antigens used decrease. Due to the shape of the round-bottom microtiter plates used, the particles collect at the lowest point and form a point.
- The test is considered positive if agglutination occurs. This can be recognized by the uniform deposition of the particles on the bottom of the microtiter plate (so-called "lawn"). The agglutination can be given semiquantitatively on a scale from 1 to 4.
Interpretation of the results
Since IgM antibodies are the first to be formed in the event of an infection, a positive result can indicate a new infection with Toxoplasma gondii. Such a new infection can cause problems during pregnancy. PCR , immunofluorescence tests or ELISA can also be used for further clarification . See also Toxoplasma gondii .
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- G. Desmonts, Y. Naot, JS Remington: Immunoglobulin M-immunosorbent agglutination assay for diagnosis of infectious diseases: diagnosis of acute congenital and acquired Toxoplasma infections. In: Journal of clinical microbiology. Volume 14, Number 5, November 1981, pp. 486-491, ISSN 0095-1137 . PMID 7031082 . PMC 273974 (free full text).
