Via Google cache I could retrieve a mangled OCR version of the text, which I fixed and added here below. I have also attached the PDF to view a table with test results.
IGeneX, Inc. Reference Laboratory
Specializing in Lyme and Other Tick-borne Diseases
31 kDa Epitope Test
31kDA Epitope Confirmation Test (Sensitivity > 97% in Late Lyme; Speciﬁcity > 98%)
The Lyme IgG or IgM 31 kDA Epitope test is a qualitative immunoblot assay that determines whether the 31kDA band present on a Lyme IgG or IgM western blot is due to B. burgdorferi specific antibody or not. B. burgdorferi specific epitope 31kDa antigen is denatured and separated by SDS polyacrylamide gel electrophoresis, blotted onto nitrocellulose membranes and cut into strips for the use of Lyme 31 kDA Epitope Test. It is known that Western blots, especially IgM, can give false positive results with some viruses. This test would be very useful to rule out false positives when the 31kDa band is present on the Western blots.
Patient serum is incubated with 31kDA recombinant epitope on Western Blot strips. If the 31kDa specific antibody to B. burgdorferi antigen is present, they will bind to the corresponding epitope band. After washing the unbound serum off the strip, the bound B. burgdorferi specific antibody reacts with alkaline phosphatase conjugated goat anti-human antibody (IgG or IgM). After washing the unbound conjugated antibody, the strip reacts with BCIP/NBT, a chromogenic substrate. A dark purple colored precipitate will develop on the antigen-antibody complexes. Bands are visualized, scored for intensity relative to the positive and negative controls.
Specificity and Sensitivity
The IGeneX Lyme Western blots determine whether a patient was exposed to B. burgdorferi or not. The IgG or IgM Western blot has an overall specificity of >96%; and the combined IgG and IgM Western Blots have a sensitivity of 92%. This is based on a study performed on 142 well characterized serum samples. The Lyme Western blot strips have bound B. burgdorferi proteins that are separated by molecular weight. Therefore, non-specific proteins present in the B. burgdorferi lysate co-migrate with B. burgdorferi specific proteins. The non-specific co-migrating proteins can give false positive results as has been demonstrated by us and others.
When we tested Lyme Western blots against a panel of 94 sera from patients with viral infections (confirmed by presence of antibodies to viruses), the assay specificity for Lyme Western blot IgG dropped to 90% and IgM to 81%. The Lyme IgG Western blot bands 31kDa Epitope test improved the specificity for IgG to >97% and for lgM >98% (See table below). In addition when a panel of very well characterized 30 sera from patients with neuroborreliosis, that were part of an NIH study, (provided by Dr. Fallon, Columbia University) were tested, the assay sensitivity was >97% (29/30 were positive).
Based on this data, we recommend that further testing is not necessary if in addition to 31kDa bands, two of the following bands (23-25, 34, 39, 41 and 83-93 kDa), are present on the Western blot. Otherwise, the 31kDA Epitope test should be used to confirm whether the 31kDa bands present on the Lyme Western blots are due to B. burgdorferi specific antibodies or not. If the 31kDa confirmation test is negative, we recommend that patient’s sera be tested for viral antibodies.
Specificity against Viruses
[see attached PDF for table with specificity test results]
Test #, Test Description, Specimen
488, 31 kDa Epitope Test - IgM*, Positive 31 kDa sample previously tested by Western Blot at lGeneX
489, 31 kDaEpitope Test- IgG*, Positive 31 kDa sample previously tested by Western Blot at lGeneX
*Not currently available to NY Residents
795/797 San Antonio Rd, Palo Alto, CA 94303, 800/832-3200, igenex.com, 09/08