A method for diagnosing a limbic encephalitis, PNS, encephaloymyelitis, leukoencephalopathy, retinitis or optic atrophy, includes detecting a bornavirus in a sample, preferably from the group comprising mammalian 2 bornavirus, even more preferably VSBV-1, and mammalian 1 bornavirus, even more preferably BoDV-1; to a carrier containing a means for the capture of an antibody against at least one polypeptide selected from the group of BoDV-1-N, BoDV-1-P, VSBV-N and VSBV-P. A kit contains the carrier and a means for the detection of a captured antibody and a control for the detection of the presence of a sample. The carrier or kit or of a primer can be used for the detection of a bornavirus or a probe can be used for the diagnosis of an encephalitis, for the prognostication of post-transplantation complications, for the monitoring of a therapy of an encephalitis or of post-transplantation complications or for the differentiation between an autoimmune encephalitis and an encephalitis caused by infection.