|Values are valid only on day of printing.|
The VIDAS TOXO IgM system (bioMerieux Inc., Durham, NC) is an automated serologic test for use on the VIDAS analyzer, which employs the enzyme-linked fluorescence assay (ELFA) technique. The assay uses a 2-step EIA sandwich method. A pipette tip-like device, the Solid Phase Receptacle (SPR) is coated with goat anti-IgM antibodies and serves as the solid phase as well as the pipettor for the assay. The sample is diluted and cycled in and out of the SPR. Subsequently Toxoplasma gondii antigen, followed by mouse, anti-Toxoplasma gondii antigen conjugated antibodies are cycled through the SPR. A fluorescent substrate, 4-methylumbelliferyl phosphate, is added to the SPR, which catalyzes the conversion of the conjugated substrate to a fluorescent product. The intensity of the fluorescence is measured by the optical scanner of the instrument.(Package insert: VIDAS TOXO IgM, BioMerieux, Durham, NC)
The BioPlex 2200 Toxoplasma IgG assays uses multiplex flow immunoassay technology. Briefly, Toxoplasma antigen-coated fluorescent beads are mixed with an aliquot of patient sample and sample diluent and incubated at 37 degrees C. During this time IgG anti-Toxoplasma antibodies in the specimen will bind to the Toxoplasma antigen on the beads. After a wash cycle, a fluorescently labeled antihuman IgG-antibody conjugate is added to the mixture and incubated at 37 degrees C. Following a wash step to remove unbound conjugate, the bead mixture is passed through a detector that identifies the bead based on dye fluorescence and determines the amount of antibody captured by the antigen based on fluorescence of the antihuman IgG conjugate. Raw data is calculated in relative fluorescence intensity and is converted to an antibody index (AI) for interpretation.
Three additional dyed beads, an internal standard bead, a serum verification bead, and a reagent black bead are present in each reaction mixture to verify detector response, the addition of serum to the reaction vessel and the absence of significant nonspecific binding in serum, respectively.(Package insert: BioPlex 2200 System, ToRC IgG, Bio-Rad Laboratories, Clinical Diagnostics Group, Hercules, CA)
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