Toxo IgM
Enzyme ImmunoAssay (ELISA) for the determination of IgM antibodies to Toxoplasma gondii or T.gondii in human plasma and sera with the "capture" system.
Toxoplasma gondii is an obligate intracellular protozoan parasite that is probably capable of infecting all species of mammals, including man.
The detection of IgM antibodies to T.gondii is particularly helpful for the diagnosis of acute infections in “risk” individuals, in association with AIDS, organ transplantation and pregnancy. As most of T.gondii infections are mild or asymptomatic in otherwise healthy individuals, the detection of T.gondii specific IgM antibodies, in absence of detectable specific IgG, has become important for the monitoring of acute infections in pregnant women, as the parasite can lead to severe birth defects.
Moreover, as T.gondii infections are most severe in immunocompromised patients, where the disease can be fatal, acute infections due to this parasite have to be distinguished from other disorders.
Recently developed IgM capture assays provide the clinician with a helpful and reliable test, not affected by the rheumatoid factor as it happens to be in classic sandwich tests.
The assay is based on the principle of “IgM capture” where IgM class antibodies in the sample are first captured by the solid phase coated with anti hIgM antibody.
After washing out all the other components of the sample and in particular IgG antibodies, the specific IgM captured on the solid phase are detected by the addition of a preparation of inactivated T.gondii, labeled with a specific monoclonal antibody conjugated with peroxidase (HRP).
After incubation, microwells are washed to remove unbound conjugate and then the chromogen/substrate is added. In the presence of peroxidase the colorless substrate is hydrolysed to a colored end-product, whose optical density may be detected and is proportional to the amount of IgM antibodies to T.gondii present in the sample.
A system is described how to control whether the positivity shown by a sample is true or not (Confirmation Test), helpful for the clinician to make a correct interpretation of results.
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