Figure 1Normal and disease-causing prions structures [20].
Table 1Transmissible spongiform encephalopathy in humans and animals [15,25]
Disease name |
Animal species |
Reported year |
Scrapie |
Sheep |
1732 |
Creutzfeldt–Jakob disease |
Humans |
1920 |
Transmissible mink encephalopathy |
Mink |
1947 |
Chronic wasting disease |
Deer |
1967 |
Bovine spongiform encephalopathy |
Cows |
1986 |
Feline spongiform encephalopathy |
Cats |
1990 |
Variant Creutzfldte–Jakob disease |
Humans |
1996 |
Table 2Various types of Creutzfeldt–Jakob disease [50]
Type of disease |
Cause |
Sporadic CJD |
Sporadic. The cause is not known; it is not common but is found worldwide and is generally found in old people; one in 1 million spontaneous conversion |
Familial CJD |
Genetic. It is caused by mutation of a prion gene; 5–10% of all cases of TSE. It is also called genetic CJD |
Iatrogenic CJD |
Acquired. It is transmitted through medical procedures including surgery, transplantation, and blood transfusion |
Variant CJD |
Acquired. It was discovered in 1996; it is assumed that it is acquired by the consumption of pathogenic prions from BSE-infected beef (it was initially called new variant CJD) |
Table 3Incidence of vCJD until August 2012
Country |
Number of primary cases |
Number of secondary cases: blood transfusion |
Cumulative residence in the UK for >6 months during 1980–1996 |
Canada |
2 |
0 |
1 |
France |
27 |
0 |
1 |
Italy |
2 |
0 |
0 |
Japan |
1 |
0 |
0 |
Netherland |
3 |
0 |
0 |
Portugal |
2 |
0 |
0 |
Republic of Ireland |
4 |
0 |
2 |
Saudi Arabia |
1 |
0 |
0 |
Spain |
5 |
0 |
0 |
Taiwan |
1 |
0 |
1 |
UK |
173 |
3 |
176 |
USA |
3 |
0 |
2 |
Total |
224 |
3 |
183 |
Table 4Prion detection methods for the diagnosis of BSE [63,64]
Method |
Specimen |
Detection of |
Rapid test using ELISA |
Fresh brain tissue |
PrPSc antigen |
Histopathological test |
Formalin-fixed brain tissue |
Spongiform in brain tissue |
Immunohistochemistry |
Formalin-fixed brain tissue |
PrPSc antigen |
Western blot |
Fresh brain tissue |
PrPSc antigen |
Electron microscopy |
Fresh brain tissue |
Scrapie-associated fibril |
Bioassay |
Fresh tissue |
PrPSc and infectivity |
Table 5Approved and most frequently used rapid tests for the detection of BSE [19,63,64]
Product name (company) |
Diagnostic method |
Authorized country |
Note |
Prionics-Check |
Western blot using the proteinase–processed specimen using an antigen to prion |
EU |
Specimen: 0.5 g obex tissue |
Western test (Prionics AG) |
|
USA |
Limit: ∼5.0–20 pmol |
|
Test period: ∼6–8 h |
Prionics-Check LIA (Prionics AG) |
Sandwich ELISA |
EU |
Specimen: 0.5 g obex tissue |
USA |
Limit: ∼1.0–5.0 pmol |
|
Test period: 4 h |
Bio-Rad test (Bio-Rad) |
Sandwich ELISA |
EU |
Specimen: 0.35 g obex tissue |
USA |
Limit: ∼0.5–2.0 pmol |
Japan |
Test period: 6 h |
Enfer test (Abbott Labs) |
Simple ELISA |
EU |
Limit: ∼1–10 pmol |
USA |
Test period: 4 h |
Japan |
|
CDI test (Impro Biotechnology) |
Immunity analysis based on the structural differences |
EU |
Limit: ∼0.5–5.0 pmol |
USA |
Test period: 8 h |
Japan |
No proteinase K |
Herd-check (IDEXX Laboratories) |
Immunity analysis after separating the variant prion (PrPSc) from brain tissue specimens |
USA |
Test period: ∼4–5hours |
|
No proteinase K |