IMMUNOBLOT REACTIVITIES OF DIFFERENT LYME DISEASE SPECIFIC ANTIGENS TO ANTI-BORRELIA BURGDORFERI IgG ANTIBODIES

Background: Lyme disease is a vector-borne disease with increasing incidences in last years. It is the most common tick-borne infection in Bulgaria, caused by Borrelia burgdorferi sensu lato (Bbsl) complex after a bite from Ixodes ricinus tick. The aim of this study is to identify the most common antigens targeted by specific IgG antibodies produced in response toBbsl infection in humans. Material and methods: Serum samples (n=220), pre-tested as positive or borderline by ELISA for specific anti-Borrelia IgG antibodies, were tested with a commercially available confirmatory immunoblot kit. Results: The most common specific anti-Borrelia IgG antibodies reacted against: p41 (97.1%), VlsE (average of 62.1% across the three variants: VlsE Bg, VlsE Bb and VlsE Ba), p83 (32.4%), p39 (30.4%) and OspC (22.6%) among the positively interpreted immunoblot tests. The weak positive bands among the positively interpreted blot tests were: OspC (17.7%), VlsE (average of 10.5% across the three variants), p21 (9.8%), p39 (8.8%), p83 (6.9%). Conclusions: This study analysed the most common antigens targeted by specific IgG antibodies synthesised after Bbsl infection in humans from all 28 provinces of Bulgaria. It was probably cross-reactive antibodies that appeared in some cases with weak positive bands. The data obtained from the confirmed cases of Lyme disease, based on the different distribution of immunoblot bands allow for a better understanding the peculiarities of this disease. The use of new specific antigens for confirmatory tests based on selected conserved fragments within Bbsl leads to development of more sensitive and specific serological analysеs.