Comparative pathological study of the murine brain after experimental infection with classical rabies virus and European bat lyssaviruses.

European bat lyssaviruses (EBLVs) types 1 (EBLV-1) and 2 (EBLV-2) cause rabies in terrestrial species, but the pathological changes associated with neuroinvasion have yet to be fully elucidated. Swiss OF-1 mice were inoculated peripherally with strain RV61 (classical rabies virus), RV1423 (EBLV-1) or RV1332 (EBLV-2) to compare the nature and extent of histopathological changes produced. Inoculated animals developed varying degrees of non-suppurative encephalitis, and lyssavirus infection was confirmed by the detection of viral antigen. The lesions produced, which included perivascular cuffs and gliosis, were more severe after RV1423 or RV1332 infection than after RV61 infection. Perivascular cuffs were mainly localized to caudal brain regions, irrespective of the infecting strain; after RV1332 infection, however, they were particularly abundant, being composed of large numbers of inflammatory cells. T cells were the predominant lymphocytic component of the inflammatory infiltrate in both the Virchow-Robin space and the brain parenchyma. Viral antigen, which was widespread throughout the brain, was apparently unrelated to the degree of cuffing. The study suggested that there was increased immune activation after inoculation with strain RV1423 or RV1332, particularly the latter, but that this did not affect the final outcome.