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Product Name: Borrelia burgdorferi IgM ? ELISA (recombinant)
# of Samples: 1 x 96 Assays
Intended Use: The recombinant Borrelia burgdorferi IgM-ELISA is intended for the qualitative determination of IgM class antibodies against Borrelia burgdorferi in human serum or plasma (citrate) offering increased diagnostic specificity and sensitivity by employing immunodominant antigens. In combination with the recombinant IgG ELISA each clinical phase of Lyme disease - from Erythma chronicum migrans over Bannwarth-Syndrom up to Lyme arthritis - may be detected even in borderland cases providing unerring results and diagnostic aid for the clinical staff.
Introduction: Spirochetes are motile bacteria with a periplasmatic axial filament. All pathogenic species belong to the family Treponemataceae, which includes the three genera: Treponema, Borrelia, and Leptospira. The Treponemae are extremely long, flexible, filamentous cells that are usually held in a characteristic spiral, or coiled-spring shape. Borreliae are the largest Treponemataceae with very coarse and irregular spirals. Borrelia burgdorferi, the causative agent of Lyme disease, is transmitted mainly by ticks but probably also by other blood-sucking insects. Habitats are the wooded, humid and temperate regions of North America, Europe, North Africa, Australia and Japan; foresters, farmers, and anybody entering infested forests may be affected.
The degree of contamination of ticks amounts to 3-60% dependent on seasonal and regional differences; up to 30% of the population may be infected (about 1500 cases annually in USA, several hundred in Europe).
Because of its multisystemic character, unequivocal diagnosis of Lyme disease is difficult. Only early detection permits efficient control by antibiotics, since in the chronic phase borreliae are nearly inaccessible. The presence of bacteria resp. infection may be identified by:
Microscopy: Giemsa or Wright-stained blood smears
Serology: Detection of antibodies by IF, ELISA, immunoblotting
Principles of the assay: The major constituent of B. burgdorferi flagella is flagellin (41 kDa, p41). Whereas the lipoprotein OspC (22 kDa, p22) within the outer membrane of the spirochete induces an early antibody formation in the ECM-phase of Lyme disease. Recombinant p41i is included in the presented antigens to avoid crossreactivity with antibodies of syphilitic sera.
The Borrelia burgdorferi IgM-ELISA contains the recombinant epitope OspC of the phylum PKo (B. afzelii) and 20047 (B. garinii) and p41i of the phylum PBi (B. garinii).
Microtiter strip wells are pre-coated with recombinant Borrelia burgdorferi antigens. Diluted patient specimens and ready to use controls are added to these wells and antibodies recognizing the immobilized B. burgdorferi antigen bind during the first incubation. After washing the wells to remove all unbound sample and control material horseradish peroxidase labelled anti-human IgM conjugate is added. During a second incubation this conjugate binds to the captured antibodies, and the excess unbound conjugate is removed by a further wash step. The immune complex formed by the bound conjugate is visualized with TMB Substrate Solution which gives a blue reaction product, the intensity of which is proportional to the amount of B. burgdorferi-specific IgM antibody in the patient specimen. Sulphuric acid is added to each well to stop the reaction. This produces a yellow endpoint colour. Absorbance at 450 nm is read using an ELISA microwell plate reader.
Storage and Stability: The reagents are stable up to the expiry date stated on the label when stored at 2...8 °C.
Limitations of the Test: Bacterial contamination or repeated freeze-thaw cycles of the specimen may affect the absorbance values. Diagnosis of an infectious disease should not be established on the basis of a single test result. A precise diagnosis should take into consideration clinical history, symptomatology as well as serological data. In immunsuppremized patients and newborns serological data only have restricted value. A neg. result (IgM or IgG) cannot exclude an infection with B. burgdorferi. Especially in the early phase of infection there is the possibility that none or no detection quantities of the antibodies do exist. In the case of infection or a grey zone result we recommend a further sample after 2-3 weeks. A positive result of IgM does not always mean that an acute infection exists because the antibodies of a previous infection can persist. The use of recombinant antigens avoid extensively cross reactions with the following antibodies: Treponema pallidum, Leptospira, Borrelia recurrentis. Antibodies of a lues-infection to p41i were occasionally determinated. Therefore a lues-infection should be excluded.
References Johnson R.C.,Schmid G.P.,Hyde F.W.,Steigerwaldt A.G.,Brenner D.J.(1984) Borrelia burgdorferi sp.nov.:etiologic agent of Lyme disease.Int J Syst Bacteriol 34,496-497AsbrinkE.,Hovmark A.(1988) Early and late cutaneous manifestations of Ixodes-born borreliosis (erythema migrans borreliosis, Lyme Borreliose).Ann NY Acad Sci 539,4-15Karlson M.,Hovind-Hougan K.,Svenungsen B.,Stiernsted G.(1990) Cultivation and characterization of Spirochetes from cerebrospinal fluid of patients with Lyme borreliosis. J Clin Microbiol 28, 473-479Preac-Mursicd V.,Wilske B.,Schierz G. (1986) Eurpean Borrelia Burgdorferi isolated from human and ticks:Culture conditions and antibiotic susceptibility.Zbl Bakt Hyg A 263,112-118WilskeB.,Preac-Mursic V.,FuchsR.,Schierz G.(1990) Diagnostik der Lyme Borreliose.Diagnose und Labor,Laboratoriumsblätter 40,24-36