Objectives:

For diagnosis of Lyme borreliosis (LB) a two-step approach is recommended by CDC and DGHM (screening ELISA followed by immunoblot (IB) in case of reactive ELISA). Though Borrelia IBs are widely used, they are still poorly defined regarding sensitivity, specificity and standardisation. A recently described recombinant Western immunoblot (WIB) complemented with Borrelia antigens produced in vivo but not in culture (i.e. VlsE) could improve previous tests (1). Here a recombinant Borrelia line IB (LIB) was developed where each recombinant antigen is separately detectable, even those antigens with identical molecular weight.

Methods:

The following recombinant IgG and IgM IBs were compared: (a) The WIB described in (1) with p83/p100 (strain PKo, B. afzelii), p58 (strain PBi, B. garinii OspA-type 4), BmpA (strains PKa2, B. burgdorferi sensu stricto, PKo, and PBi), VlsE (strain PKa2), OspC (strains PKa2, PKo, PBi, and B. garinii strain 20047), and DbpA (strains PKo and PBr, B. garinii OspA-type 3). (b) The LIB with all antigens of the WIB and in addition VlsE (strains PKo and PBi), OspC (strain PLe, B. afzelii) and DbpA (strains B31 and PBi). To verify sensitivity and specificity, 65 sera of patients with early LB (50 early neuroborreliosis, 15 Erythema migrans) and 110 control sera (60 blood donors, 10 rheumatoid factor positive, 10 syphilis patients and 30 patients with fever of unknown origin) were studied.

Results:

IB interpretation criteria defining a serum as positive with at least two reactive bands or in case of IgM at least one strong OspC band were used (2). Sensitivity significantly increased from 63% (WIB) to 80% (LIB) for IgG and from 46% (WIB) to 69% (LIB) for IgM while specificity remained unchanged (99% for IgG tests and 98% for IgM tests). The increase of sensitivity was mainly due to the line blot technique, which allows detection and identification of antibodies differently reactive with homologues of the same protein.

Conclusion:

The LIB is more sensitive than the WIB for both IgG and IgM antibody detection in acute LB while specificity remains unchanged. The LIB is better to standardise and results are easier to interpret.

References

Schulte-Spechtel, U, et alJ. Clin Microbiol, 41(2003)1299.

Wilske, B, et alMIQ 12 Lyme borreliosis, Urban &Fischer, 2000.