The Tick-Borne Relapsing Fever (TBRF) ImmunoBlot is a qualitative immunoassay in which antibodies specific to the TBRF Borrelia antigens on a membrane strip are visualized. It is a qualitative test and is more sensitive and specific than the IFA and traditional Western Blot tests. In early or late stage of the disease when antibody levels are very low, ImmunoBlot can be positive whereas IFA tests can be negative.
The TBRF ImmunoBlot assay is based upon an antigen-antibody complex formation in the following steps:
- Binding of anti-TBRF Borreliaspecific antibodies in human serum to the ImmunoBlot strip. ImmunoBlot strip is a membrane strip with fixed TBRF Borrelia recombinant antigens on it.
- Binding of enzyme labeled anti-humanIgG or IgM antibodies to the human anti–TBRF Borrelia antibodies bound to fixed TBRF Borrelia antigens on the membrane.
- Reaction with BCIP/NBT, a chromogenic substratewith bound antibodies on the strip. A dark purple colored precipitate (band) develops on the antigen-antibody complexes.