Transmissible spongiform infectivity

During the preparation of the bovine bones used in the production of gelatin, specified risk materials that could contain Transmissible Spongiform Encephalopathies (TSEs) vectors are removed. TSE infectivity is not present in... 

Race RE, Raines A, Baron TG et al (2002) Comparison of abnormal prion protein glycoform patterns from transmissible spongiform encephalopathy agent-infected deer, elk, sheep, and cattle. J Virol 76 12365-12368... 

Schmerr, M.J., Jenny, A.L., Bulgin, M.S., Miller, J.M., Hamir, A.N., Cuflip, R.C., and Goodwin, K.R. Prions have been studied by capillary electrophoresis [Use of capillary electrophoresis and fluorescent labeled peptides to detect the abnormal prion protein in the blood of animals that are infected with a transmissible spongiform encephalopathy]. J Chromatogr. A, 853, 207, 1999. 

Prion diseases In the 1990s, four patients were infected with variant Creutzfeldt-Jakob disease (vCJD) after transfusions of non-leukodepleted blood. The incubation periods in the recipients were 6.5-8.3 years after transfusion. Leukocytes are now removed from blood used for transfusion [60, 96, 9T]. Plasma products carry a low risk of transmission of transmissible spongiform encephalopathies because of production processes [96 ]. The estimated risk depends on the prion load. Of plasma products, vCJD-implicated batches of clotting factor concentrates were categorized as likely to transmit prion diseases [9T]. In the UK, and before the exclusion of the use of British plasma, the risk of prion transmission by blood was estimated to be 7-14 per 10000 patients with hemophilia, assuming a vCJD population prevalence of 1 in 10000... 

Baxter HC, Campbell GA, Whittaker AG, Jones AC, Aitken A, Simpson AH, Casey M, Bounfiff L, Gibbard L, Baxter RL. Elimination of transmissible spongiform encephalopathy infectivity and decontamination of surgical instruments by using radio-frequency gas-plasma treatment. J Gen Virol 2005 86 2393-9. 

However, the emergence of variant Creutzfeldt-Jakob disease (vCJD) in the UK and France has raised concern about a new theoretical risk of infection in patients treated with blood and blood products (198). Animal experiments in which blood from sheep infected with bovine spongiform encephalopathy and natural scrapie-infected sheep into scrapie-free recipient animals have suggested disease transmission by the blood transfusion route in 2 of 24 sheep with bovine spongiform encephalopathy and in 4 of 21 sheep with scrapie (199). Many European countries have incorporated leukodepletion of all blood products, as leukocytes are believed to play a key role in the pathogenesis of variant Creutzfeldt-Jakob disease (198). In some countries, people who have lived in the UK for a period longer than 6 months between 1980 and 1996 are excluded from blood donation (13). Furthermore, it has been shown that various steps used in the manufacture of plasma-derived products also contribute to reduced infectivity by bovine spongiform encephalopathy (198). 

Prions (small proteinaceous infectious particles) are a unique class of infectious agent causing spongiform encephalopathies such as bovine spongiform encephalopathy (BSE) in cattle and Creutzfeldt-Jakob disease (CJD) in humans. There is considerable concern about the transmission of these agents from infected animals or patients. Risk of infec-tivity is highest in brain, spinal cord and eye tissues. There are still many unknown factors regarding de-... 

The spongiform encephalopathies that we know of have characteristics of both inherited diseases and transmissible diseases. On the one hand, animals can be infected by consuming meat or other tissues that are themselves carrying mutant prion proteins. As the example of the New Zealand sheep showed, even those that are very susceptible to a prion disease can remain disease-free if they are never exposed. However, the predisposition to acquire a prion disease has a hereditary component as well. The prion protein has many known mutations, some of which render the individual very susceptible to the disease. These mutations can be tracked and they are passed along family lines. 

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