Contents


**1**

nonhuman primates) [6, 8].

sheep.

**Chapter 1**

*Ivo Nikolaev Sirakov*

**1. Introduction**

and genetic diseases.

Introductory Chapter: Prions

mechanism evolved together with the methodological advancements.

acting as a "transformer and conductor" of the infectious isoform.

no genetic determinant was detected for its development.

The cellular prion protein (PrPC) is expressed as a cell surface protein mainly in the central and peripheral nervous system, as well as in some cells and organs of the immune system (leukocytes and the spleen), the reproductive system (the testes and ovaries), and others, such as Peyer's patches in the intestinal tract, heart, lungs, and skeletal muscles, spreading to almost all parts of the body [1]. Prions were only relatively recently revealed to act as infectious agents although the diseases they cause have been known for a long time—initially attributed to toxic, genetic, and psychological factors and "unconventional viruses"—as our understanding of their

The discovery that prions are infectious agents changed the concept of protein synthesis in modern biology and built a bridge between the genesis of infectious

The normal distribution of PrPC in certain organs correlates with the pathogenesis route of some prion diseases, such as scrapie, Kuru, bovine spongiform encephalopathy (BSE), new variant Creutzfeldt-Jakob disease (vCJD), chronic wasting disease (CWD), and feline spongiform encephalopathy (FSE), probably

From a historical perspective, scrapie—as a disease of sheep—was a subject of discussion in the British parliament back in 1755; however, it was not until 1936 that Cullie and Chelle proved its contagious character by experimental infection [2]. Studies demonstrated genetic predisposition to development of the disease [3].

The disease bovine spongiform encephalopathy (BSE) was first identified and reproduced in 1986 in the United Kingdom [4]. It resulted from an incinerating technology introduced in the 1970s that worked at a lower disposal temperature and the supplementation of calf feed mixtures with meat-bone meal from scrapie

In Wisconsin, USA, in 1947, the disease transmissible mink encephalopathy (TME) was reported, arising from the use of sheep carcasses for food. Due to the cannibalism existing among minks and the passages through them, the etiological agent has undergone changes (e.g., it is nonpathogenic to mice) [2]. Another prion disease in animals is chronic wasting disease (CWD), which affects cervids including deer, elk, and moose. It was described by Williams and Young in 1980 [5], and

Feline spongiform encephalopathy (FSE) was first reported as a disease in members of family Felidae in a zoo in the UK [6] and in other carnivorous animals. Eventually, the infection was demonstrated to originate from BSE [7], the source of infection being contaminated food. BSE is also the etiological agent of diseases in Nyala, Kudu—exotic ungulate encephalopathy (EUE)—and Lemurs (NHP—BSE in

There is a direct relationship between the prion diseases in animals and humans due to the ability of BSE to jump the barrier between species (via contaminated

## **Chapter 1**
