SUPPLEMENTAL UPDATE, 1980 Model Number 20

Slow Infection by Unconventional Viruses

Human Disease: Creutzfeldt-Jakob

Disease, Kuru

Animal Model: Scrapie, Transmissible

Mink Encephalopathy

Contributed by: R. F. Marsh, DVM, Department of Veterinary Science, University of Wisconsin, Madison, WI 53706

Biologic Features

Since Sigurdsson’s original description of slow infections,’ it has been

recognized that these types of diseases which are produced by viruses may be subdivided into two general groups depending on whether they are caused by conventional or unconventional agents. The latter group of slow virus infections comprise two which affect humans: Creutzfeldt Jakob disease and kuru; and three affecting animals: scrapie, transmissible mink encephalopathy (TME), and the newly recognized chronic wasting disease of captive mule deer.2 Although the human diseases have been transmitted to several animal models, scrapie remains the animal model of choice for the study of the spongiform encephalopathies because its models are better characterized and represent a lesser human health hazard. Additionally, one of the advantages of the study of scrapie is the availability of several choices of models, each offering individual features which can be manipulated to examine different aspects of the disease:

tion periods (8 weeks) and high brain titers of infectivity (l0’°LD50/ gram) which allow for faster endpoint titrations measuring the transmissible agent.3’4 This remains necessary because of the lack of a cell culture assay and the absence of any specific immune response in infected animals. The hamster has also been found to be a useful model for the study of scrapie-induced retinopathy.5

mouse bioassay, the mouse model remains important for the study of agent-host interactions. By evaluating the responses of different inbred strains of mice to inoculation with various sources of scrapie, it has been

For reference citation — Marsh, R. F.: Slow viral Infections, Model No. 20, Supplemental Update,

1980. In Handbook: Animal Models of Human Disease. Fasc. 2. Edited by C. C. Capen, D. B.

Hackel, T. C. Jones and 0. Migaki. Registry of Comparative Pathology, Armed Forces Institute of

Pathology, Washington, DC (1980).