Detection of Borrelia burgdorferi Sensu-Lato-Specific Antibodies in Sera of Canine and Equine Origin—A Comparative Study with Two Line Immunoassays

SIMPLE SUMMARY: The causative agents of Lyme borreliosis, spirochetes from the Borrelia burgdorferi sensu lato complex, can be transmitted via various life stages of the tick, making this disease a serious concern pertaining to One Health approaches. The detection of specific antibodies against Bbsl is generally achieved by using a two-tiered test approach based on an ELISA combined with a line immunoassay (LIA). In this study, canine and equine serum samples with known antibody status were tested with two different LIAs. Results were compared in term of sensitivity, specificity, diagnostic outcome for dogs and horses, as well as of operability of the test. For canine serum samples, reliable results can be achieved with both LIAs. In contrast, the serodiagnosis of horses is still challenging, and improvements of both LIAs are recommended. ABSTRACT: Lyme borreliosis is a vector-borne disease in humans and animals caused by bacteria from the Borrelia burgdorferi sensu lato complex (Bbsl). The possible transmission of Bbsl from companion animals to humans via ticks makes this disease important in terms of One Health approaches. Thus, early and accurate diagnosis and treatment are of utmost importance. Today’s standard for the detection of specific antibodies against Bbsl is a two-tiered test system based on an ELISA for screening combined with a line immunoassay (LIA) for confirmation. In this study, 200 canine and 200 equine serum samples with known antibody status were tested with two different LIAs (A and B). Results were compared regarding sensitivity, specificity, the diagnostic outcome for dogs and horses, as well as operability of the test. The results for canine serum samples corresponded to 94.0%, making both LIAs a good choice for LB diagnostic in dogs. For equine serum samples, the agreement of both tests was 65.5%, displaying the challenge equine samples still provide in LB diagnostic. Major concerns were the interpretation of the OspA antigen (AG) signal and the use of unspecific (i.e., p100/p83) or too sensitive signals on the LIA. The operability of both LIAs was equally user-friendly. Regarding the tests’ evaluation, the scanning process provided by LIA A was a major advantage considering the comparability of the tests.