SERUM ANTIBODIES AGAINST BORRELIA-AFZELII, BORRELIA-BURGDORFERI SENSU-STRICTO AND THE 41-KILODALTON FLAGELLIN IN PATIENTS FROM A LYME BORRELIOSIS ENDEMIC AREA - ANALYSIS BY EIA AND IMMUNOBLOT

To evaluate the possible importance of antigenic heterogeneity in the serological diagnosis of Lyme borreliosis a study was performed using antigens from various Lyme Borrelia strains. Serum samples from 102 pa tients with clinical signs of the infection, all living in an endemic area in southern Sweden, were evaluated by four enzyme immune assays ( EIA). The sera were initially tested for the immunoglobulin G response to antigens from a local Borrelia afzelii strain (ACAI). Serum sample s from healthy blood donors residing in the same region were used to d efine seropositivity in the ACAI-EIA. Immunoblotting was performed wit h the ACAI antigen and the reactive bands were analysed. A serum was d efined as positive when at least four of the Borrelia specific polypep tides (OspC, OspA, OspB, p39, p41 [flagellin], p83, p94, 110 kDa) were stained. The same sera were then analysed in three other IgG enzyme i mmunoassays, one based on antigens from Borrelia burgdorferi sensu str icto B31, and another on pooled protein fractions from strains B31 and ACAI. In the third EIA, sera were analysed for antiflagellin reactivi ty (B. afzelii strain DK-1). An inconstant immune response was demonst rated in the EIAs and the seropositivity varied between 30-47% when lo w positive values were excluded, and between 38-73% if all values were included. Fifty sera (50/102) met the criteria for a positive immunob lot, but positive immunoblots were detected with both low positive and negative sera independent of antigen used in the EIAs. Antigens of th e local B. afzelii strain were found to detect a higher number of sero positive individuals, which suggests that the antibody reactivity to L yme Borrelia increases when antigens from a strain endemic in a partic ular geographical region are used. Data from this study suggest that E IA alone seems insufficient for the serodiagnosis, and antigenic heter ogeneity of Lyme Borrelia spp. influences the performance of serum ant ibody tests. The reliability of serological assays could be increased when the serum antibodies against antigens of Borrelia spp. predominan t in the local geographical region are measured.