Introduction. During the last two decades, after Sigurdsson's introduction of a new concept of an infectious process, slow virus infections of the central nervous system have developed into novel and attractive disease models (Sigurdsson, 1954). Through his studies of naturally occurring diseases in sheep, including Maedi, Visna and scrapie, Sigurdsson observed that these infections were characterized by an incubation period lasting for many months to years and a predictable protracted clinical course usually leading to death. Subsequent studies carried out by many research groups have basically confirmed Sigurdsson's concept. It was found that slow virus infections are related to unconventional and conventional agents, both of which have been associated with naturally occurring diseases in animals and man (Table 1).

The unconventional agents which have not been visualized, isolated or characterized reveal unusual biological and physico-chemical properties, exceptional for any known infectious agent. The conventional viruses, isolated from diseased brain material, resemble classical viruses, progress has been made in the understanding of the infectious process since the isolates provided an experimental basis for virological and immunological studies in these diseases.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error