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Chronic viral infections of the central nervous system.

Several subacute and chronic conditions of the central nervous system (CNS) of man and animals have been found to be of possible viral etiology. In man, these include subacute sclerosing panencephalitis, Creutzfeldt-Jakob disease, and kuru. In animals, scrapie, visna, and lymphocytic choriomeningitis have been transmitted by cell-free filtrates. The techniques of tissue culture, immunofluorescence, and electron microscopy have greatly contributed to a better understanding of the latent and masked viruses which cause these chronic infections of the CNS. The exceptionally long latent or incubation period of these neurological diseases results from an unusual virus-cell interaction.