Editorial: Koch's postulates and slow infections of the nervous system.

Animals Brain/microbiology Chronic Disease Creutzfeldt-Jakob Syndrome/etiology Disease Models, Animal Humans Kuru/etiology Leukoencephalopathy, Progressive Multifocal/etiology Measles virus/isolation & purification Microscopy, Electron Nervous System Diseases/etiology Papillomaviridae/isolation & purification Polyomaviridae Slow Virus Diseases/complications Subacute Sclerosing Panencephalitis/etiology Virus Cultivation Viruses/isolation & purification