Common Types of ToRCH Assays
ToRCH IgG & IgM Capture Assays
A ToRCH serologic test detects IgM and IgG antibodies to the ToRCH panel of infectious diseases (Toxo, Rubella, CMV and HSV). IgM is the immediate antibody that is produced once a human is exposed to a bacteria, virus or a toxin and disappears within 2-3 weeks. It is then replaced by IgG which lasts for life and provides lasting immunity. Meridian’s ToRCH antigens are suitable for IgG and IgM detection. They can be used in a range of immunoassay formats including, but not limited to, ELISA, LF, CLIA, rapid assays, and bead-based assays.
Detectable product
GENERAL ASSAY PRINCIPLE 1. Solid-phase (assay plate, beads, etc) is coated with the antigen 2. Blocking buffer is added to block the remaining binding site 3. Sample is added and patient’s IgG or IgM antibody binds to the antigen 4. Detection can either be by direct or indirect methods
INDIRECT
Substate
Secondary Antibodies
Enzyme
Blocking Reagent
Antigen Patient’s IgG or IgM Ab
INDIRECT DETECTION: uses a labeled secondary antibody for detection. The secondary antibody has specificity for human IgG or IgM.
ToRCH Rapid Anti-IgM Assays
Rapid anti-IgM assays are particularly sensitive in demonstrating IgM responses early in the illness. These assays work by binding IgM-specific antibodies in the patient’s specimen to a solid phase coated with an anti-IgM capture antibody. Soluble antigen is added in excess allowing the specific IgM antibody-antigen reaction to occur in the absence of competing immunoglobulin isotypes. Finally, a labelled detection antibody is added which has specific reactivity against the antigen. Assay sensitivity can be highly dependent on the purity of the antigen used. ELISA capture for IgM determination minimizes interference of rheumatoid factor.
GENERAL ASSAY PRINCIPLE 1. Solid-phase is coated with anti-human IgM (MAb or PAb Blocking buffer is added to block the remaining binding site) 2. IgM-specific antibodies in the patient’s sample bind to the anti-human IgM 3. Antigen (e.g. Rubella, toxo) is added in excess and a antibody- antigen-antibody complex forms 4. Detection can either be by direct or indirect methods
Substate
Detectable product
Detectable product
Enzyme
Anti-ToRCH Antigen
IgM captured from patient sample
ToRCH Antigen
Anti-human IgM antibody Recommended:
Cat# Z01235M Cat# W01258G Cat# W01259G
DIRECT DETECTION
INDIRECT DETECTION
DIRECT DETECTION: uses a labeled antigen that reacts directly with the antibody.
INDIRECT DETECTION: uses a labeled secondary antibody for detection.
4 | ToRCH REAGENTS - IgG and IgM Assay Development
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