Direct immunofluorescence as a low-budget method for brain tissue inspection in standardization of neuroborreliosis animal model in NMRI mice

Abstract

Objective. To test if the direct immunofluorescence can be used for the detection of Borrelia afzelii in brain tissue during the standardization of the animal model of neuroborreliosis in NMRI mice. Methods. The study was performed on 15 mice of NMRI strain. All mice were subcutaneously inoculated with 100 ml of BSK-H medium containing the local isolate of Borrelia afzelii. Animals were sacrificed after inoculation at III (n = 4), IV (n = 6) and V (n = 5) weeks, by cervical dislocation. In the sampled brains of mice, the presence of Borrelia was detected by direct immunofluorescence (DIF) and chain polymerization reaction (PCR). Results. The first brain tested positive for Borrelia three weeks after the inoculation. The bacteria were detected in 1 out of 4 brains (25%). After that, there was a growth in the percentage of positive results. The data showed that 3 out of 6 brains (50%) were found positive on Borrelia presence by the end of the fourth week. Whereas, in 3 out of 5 brains (60%) Borrelia was detected five weeks following the inoculation. Conclusion. According to the preliminary results, direct immunofluorescence appeared to be a practical, low budget method for following the kinetics of neuro-infection. NMRI mice could be considered as an adequate animal model for neuroborreliosis. Thus, more research is needed on the topics of infection kinetics for the period after fifth week post inoculation, as well as sensitivity and specificity of direct immunofluorescence.