Comparison of different Borrelia burgdorferi sensu lato strains for detection of immune response in patients with erythema migrans.

The aim of the present study was to establish which combination of serological method and Borrelia strain used as an antigen would provide the most appropriate demonstration of borrelial infection in patients with eythema migrans residing in Slovenia. Four different strains were chosen as antigens: two strains of B. afzelii and two strains of B. garinii which differed in their expression of the outer proteins OspA, OspB and OspC. Each individual strain was used as antigen in immunofluorescence test (IFT), enzyme-linked immunosorbent assay (EIA) with whole borrelial cells, and EIA with ultrasonicated borrelial cells. With these 12 different tests, 100 samples were examined for the presence of specific IgM and IgG antibodies: 50 sera of blood donors and 50 sera of patients with erythema migrans. The latter were further subdivided into skin culture-positive and -negative subgroups. A commercial Western blot (WB) test was performed for 26 sera of the control group and 25 sera of patients with erythema migrans. The four different methods had distinct specificity and sensitivity. The most specific approaches were IFT (100% for IgM and 90-92% for IgG) and the WB test (100% for IgM and 73% for IgG), followed by EIA with whole borrelial cells (80-98% for IgM and 76-84% for IgG) and EIA with ultrasonicated borrelial cells (76-94% for IgM and 72-80% for IgG). The sensitivity levels of all these tests were low. The most sensitive were EIA tests with whole borrelial cells (28-36% for IgM and 32-42% for IgG) followed by EIA with ultrasonicated borrelial cells (22-32% for IgM and 24-36% for IgG), the WB test (16% for IgM and 32% for IgG) and IFT (0-2% for IgM and 14-20% for IgG). The following methods gave significant differences between patients and negative controls in detecting IgM antibodies: EIA with whole borrelial cells with both B. afzelii antigens and with antigen B. garinii that expressed OspA and OspC, EIA with ultrasonicated borrelial cells with antigen B. afzelii that expressed OspA, OspB and OspC. In detecting IgG antibodies, significant differences were observed between EIA with whole borrelial cells and with antigen B. afzelii that expressed OspA and OspB. Borreliae were isolated from the skin of 34/50 (68%) patients with erythema migrans: two strains failed to grow, while 26/32 (81%) strains were identified as B. afzelii, 5/32 (16%) as B. garinii and 1/32 (3%) as B. burgdorferi sensu stricto. No statistically significant differences in serologic test results between culture-positive and -negative patients with erythema migrans were found.