In situ hybridization histochemistry in the diagnosis of viral infections of the central nervous system.

In situ hybridization histochemistry opened new perspectives for the study of viral infections of the central nervous system. Immunohistochemistry can give information about the presence of a viral infection only, if the specific viral proteins are expressed in the infected cells, while in situ hybridization can detect viral genes also in case of a latent, non-productive infection. The basic technique has to be modified according to the kind of viral nucleic acid to be displayed (genomic DNA, plus or minus strand genomic RNA, viral mRNA). For detection, the highly sensitive radioactive or the less sensitive non-radioactive (enzyme-) labels can be applied. For the determination of the cell type harbouring the virus and for correlation of viral nucleic acids with viral proteins, in situ hybridization techniques and immunohistochemistry have to be combined.