Enzyme ImmunoAssay (ELISA) for the determination of IgM antibodies to Toxoplasma gondii or T.gondii in human plasma and sera with the “capture” system. The devise is intended for the follow-up of T.gondii infected patients and for the monitoring of risk of neonatal defects due to T.gondii infection during pregnancy. For “in vitro” diagnostic use only.
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.