Spongiform Encephalopathy Research Articles

Prion infections of animals: safety of food and medicinal raw materials of animal origin. Up-to-date data

Prion infections of humans and animals are absolutely fatal. The cellular prion protein retains its antigenicity during the transition to the prion isoform; therefore, animals affected by prions do not respond to them with defensive reactions in the form of inflammation and the production of antibodies, which makes it difficult to diagnose the disease in vivo. In affected animals, prions accumulate in the nervous, lymphoreticular and muscle tissues and are released into the environment, in which they remain for many years. The resistance of prions to physical and chemical factors does not allow them to be inactivated in food by heat or radiation. Zoonoticity has been proven only for the causative agent of bovine spongiform encephalopathy, to which sheep, goats and pigs are susceptible. Sheep scrapie and chronic wasting deer disease occur widely in natural conditions in the form of enzootics and are similar in many characteristics. The zoonotic nature of their pathogens has not been proven.

Variation in the PRNP gene of Pere David’s deer (Elaphurus davidianus) may impact genetic vulnerability to chronic wasting disease

Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy caused by prions that has spread across cervid species in North America since the 1960s and has recently been detected in Eurasian cervids. The Association of Zoos and Aquariums (AZA) considers CWD to be of major concern for cervids in AZA-accredited facilities because of the indirect transmission risk of the disease and the impact of CWD regulatory protocols on captive breeding programs. Vulnerability to CWD is affected by variation in the PRNP gene that encodes the prion protein. We therefore sequenced PRNP in Pere David’s deer (Elaphurus davidianus), a species that was extinct in the wild for more than a century and descends from ca. 11 founders. In 27 individuals, we detected two PRNP haplotypes, designated Elad1 (51 of 54 sequences) and Elad2 (3 of 54 sequences). The two haplotypes are separated by four single nucleotide polymorphisms (SNPs), three of which are non-synonymous. Both Elad1 and Elad2 have polymorphisms that in other cervid taxa are associated with reduced vulnerability to CWD. The two haplotypes are more similar in sequence to PRNP in other cervids than to each other. This suggests that PRNP in cervids may have been under long-term balancing selection, as has been shown for PRNP in non-cervid taxa, and which could account for the presence of multiple haplotypes among founders. There may be a fitness benefit in maintaining both PRNP haplotypes in the species because variation in the prion protein amino acid sequence can limit transmission of CWD.

Prion protein complexed to a DNA aptamer induce behavioral and synapse dysfunction in mice

Conversion of the cellular prion protein (PrPC) into the scrapie form (PrPSc) is the leading step to the development of transmissible spongiform encephalopathies (TSEs), still incurable neurodegenerative disorders. Interaction of PrPC with cellular and synthetic ligands that induce formation of scrapie-like conformations has been deeply investigated in vitro. Different nucleic acid (NA) sequences bind PrP and convert it to β-sheet-rich or unfolded species; among such NAs, a 21-mer double-stranded DNA, D67, was shown to induce formation of PrP aggregates that were cytotoxic. However, in vivo effects of these PrP-DNA complexes were not explored. Herein, aggregates of recombinant full-length PrP (rPrP23-231) induced by interaction with the D67 aptamer were inoculated into the lateral ventricle of Swiss mice and acute effects were investigated. The aggregates had no influence on emotional, locomotor and motor behavior of mice. In contrast, mice developed cognitive impairment and hippocampal synapse loss, which was accompanied by intense activation of glial cells in this brain region. Our results suggest that the i.c.v. injection of rPrP:D67 aggregates is an interesting model to study the neurotoxicity of aggregated PrP in vivo, and that glial cell activation may be an important step for behavioral and cognitive dysfunction in prion diseases.

The Role of the Nasal Cavity in the Pathogenesis of Prion Diseases.

Prion diseases, or transmissible spongiform encephalopathies (TSEs), are a class of fatal neurodegenerative diseases caused by the entry and spread of infectious prion proteins (PrPSc) in the central nervous system (CNS). These diseases are endemic to certain mammalian animal species that use their sense of smell for a variety of purposes and therefore expose their nasal cavity (NC) to PrPSc in the environment. Prion diseases that affect humans are either inherited due to a mutation of the gene that encodes the prion protein, acquired by exposure to contaminated tissues or medical devices, or develop without a known cause (referred to as sporadic). The purpose of this review is to identify components of the NC that are involved in prion transport and to summarize the evidence that the NC serves as a route of entry (centripetal spread) and/or a source of shedding (centrifugal spread) of PrPSc, and thus plays a role in the pathogenesis of the TSEs.

Creutzfeldt-Jakob Disease in South West Sydney 2014–2020: An Unusually High Incidence of a Rare Disease

Introduction: Creutzfeldt-Jakob disease (CJD), a spongiform encephalopathy, caused by a transmissible misfolded cellular prion protein, is a rapidly progressive, debilitating neurodegenerative disorder with no effective treatment. The estimated global incidence is at 1/million inhabitants. This retrospective study examined the incidence of CJD in South Western Sydney Local Health District (SWSLHD) from 2014 to 2020. Background: SWSLHD had an estimated population of 1,038,534 in 2020, with CJD data being limited. Methods: The New South Wales (NSW) Health Information Exchange (HIE) database, for all admissions with CJD diagnoses in SWSLHD, between 2014 and 2020, was reviewed according to the WHO diagnostic criteria, consistent with the Australian national CJD registry. Only probable CJD cases were included. Incidence was calculated based on the projected SWSLHD population. Results: Thirty-five patients, diagnosed with CJD, were identified. Each was evaluated by 2 independent investigators, including clinical presentation, MRI, EEGs, 14-3-3, and RT-QuIC results, before assigning CJD-probable status. Four failed the CJD criteria and were excluded. Of the 31 CJD-probable cases, most (59%) were male and older (37%, range 61–70 years). The incidence rate peaked at 9/million in 2017 and was above 2/million, throughout the 7 years, with an average of 4.859/million/year. Conclusions: The incidence of CJD, in SWSLHD, exceeds the national average of 1/million. Cost-effective, adequate diagnostic and screening tools, implementable over a large population, will become increasingly essential.

Reduced SOD2 expression does not influence prion disease course or pathology in mice.

Prion diseases are progressive, neurodegenerative diseases affecting humans and animals. Also known as the transmissible spongiform encephalopathies, for the hallmark spongiform change seen in the brain, these diseases manifest increased oxidative damage early in disease and changes in antioxidant enzymes in terminal brain tissue. Superoxide dismutase 2 (SOD2) is an antioxidant enzyme that is critical for life. SOD2 knock-out mice can only be kept alive for several weeks post-birth and only with antioxidant therapy. However, this results in the development of a spongiform encephalopathy. Consequently, we hypothesized that reduced levels of SOD2 may accelerate prion disease progression and play a critical role in the formation of spongiform change. Using SOD2 heterozygous knock-out and litter mate wild-type controls, we examined neuronal long-term potentiation, disease duration, pathology, and degree of spongiform change in mice infected with three strains of mouse adapted scrapie. No influence of the reduced SOD2 expression was observed in any parameter measured for any strain. We conclude that changes relating to SOD2 during prion disease are most likely secondary to the disease processes causing toxicity and do not influence the development of spongiform pathology.

Zn(II) binding causes interdomain changes in the structure and flexibility of the human prion protein

The cellular prion protein (PrPC) is a mainly α-helical 208-residue protein located in the pre- and postsynaptic membranes. For unknown reasons, PrPC can undergo a structural transition into a toxic, β-sheet rich scrapie isoform (PrPSc) that is responsible for transmissible spongiform encephalopathies (TSEs). Metal ions seem to play an important role in the structural conversion. PrPC binds Zn(II) ions and may be involved in metal ion transport and zinc homeostasis. Here, we use multiple biophysical techniques including optical and NMR spectroscopy, molecular dynamics simulations, and small angle X-ray scattering to characterize interactions between human PrPC and Zn(II) ions. Binding of a single Zn(II) ion to the PrPC N-terminal domain via four His residues from the octarepeat region induces a structural transition in the C-terminal α-helices 2 and 3, promotes interaction between the N-terminal and C-terminal domains, reduces the folded protein size, and modifies the internal structural dynamics. As our results suggest that PrPC can bind Zn(II) under physiological conditions, these effects could be important for the physiological function of PrPC.

The European Union summary report on surveillance for the presence of transmissible spongiform encephalopathies (TSE) in 2020.

This report presents the results of surveillance on transmissible spongiform encephalopathies (TSE) in cattle, sheep, goats, cervids and other species, and genotyping in sheep, carried out in 2020 by 27 Member States (MS, EU27), the United Kingdom (UK) and other seven non‐EU countries: Bosnia and Herzegovina, Iceland, Montenegro, North Macedonia, Norway, Serbia and Switzerland. In total, 1,122,671 cattle were tested by EU27 and the UK (−2.4%, compared with 2019), and 51,775 cattle by the other seven non‐EU, with three cases of H‐BSE in France, Ireland and Spain, and two L‐BSE in France and Switzerland. In total, 332,579 sheep and 120,615 goats were tested in the EU27 and the UK (−1.6% and −16%, respectively). In sheep, 688 cases of scrapie were reported by 16 MS and the UK: 589 classical scrapie (CS) by seven MS [81 index cases (IC), one of ARR/ARR genotype and 97% with genotypes of susceptible groups], 98 atypical scrapie (AS) (88 IC) by 14 MS and the UK, and one CH1641‐like. In addition, Italy reported 12 inconclusive cases. In total, 26,053 sheep and 712 goats were tested in the other non‐EU countries with 53 CS in Iceland and 12 AS in Norway. Random genotyping was reported by nine MS: with Cyprus excluded, 8.8% carried the genotypes of susceptible groups. In goats, 328 cases of scrapie were reported: 319 CS (52 IC) by six MS and the UK, and nine AS (9 IC) by five MS. The last of the 3‐year surveillance programme for chronic wasting disease (CWD) in Estonia, Finland, Latvia, Lithuania, Poland and Sweden resulted in 6,974 tested cervids and two CWD cases in wild moose, in Finland and Sweden. Other six MS and the UK tested 2,197 cervids, all negative. Norway tested 22,528 cervids of which one wild moose and one wild reindeer were positive. In total, 101 animals from three other species tested negative in Finland.

Annual Report of the Scientific Network on BSE‐TSE 2021

Establishing a system of Networks of organisations operating in the fields within EFSA’s mission is among the tasks of EFSA, according to Regulation (EC) No 178/2002, in order to facilitate a scientific cooperation framework by the coordination of activities, the exchange of information, the development and implementation of joint projects, the exchange of expertise and best practices. The EFSA Scientific Network on bovine spongiform encephalopathies and other transmissible spongiform encephalopathies (BSE-TSE) was established in 2006 and held its 16th annual meeting on 18-19 October 2021, as a web-meeting. The meeting served as an opportunity to exchange scientific information on BSE-TSE related issues among EU Member States, countries from the European Free Trade Association, EU candidate countries, EFSA, the European Commission (EC) and ad hoc participants [in the 2021 meeting, represented by the World Organisation for Animal Health (OIE)]. The topics discussed included: update on the VKM opinion on zoonotic potential of CWD, update on the situation and surveillance of CWD in Sweden, review of the control measures of CWD in Norway in the last five years (lessons learnt), the outputs of a risk assessment on the lift of the feed ban by ANSES, the prevalence in Britain of abnormal prion protein in human appendices (historical perspective and latest results), the new mandate of EFSA Scientific Networks 2021-2023 and joint activities of the BSE/TSE Network, recent and ongoing activities on TSE of EFSA, OIE and EC, as well as the preliminary results of the 2020 EU TSE summary report.

Variant CJD: Reflections a Quarter of a Century on.

Twenty-five years has now passed since variant Creutzfeldt-Jakob disease (vCJD) was first described in the United Kingdom (UK). Early epidemiological, neuropathological and biochemical investigations suggested that vCJD represented a new zoonotic form of human prion disease resulting from dietary exposure to the bovine spongiform encephalopathy (BSE) agent. This hypothesis has since been confirmed though a large body of experimental evidence, predominantly using animal models of the disease. Today, the clinical, pathological and biochemical phenotype of vCJD is well characterized and demonstrates a unique and remarkably consistent pattern between individual cases when compared to other human prion diseases. While the numbers of vCJD cases remain reassuringly low, with 178 primary vCJD cases reported in the UK and a further 54 reported worldwide, concerns remain over the possible appearance of new vCJD cases in other genetic cohorts and the numbers of asymptomatic individuals in the population harboring vCJD infectivity. This review will provide a historical perspective on vCJD, examining the origins of this acquired prion disease and its association with BSE. We will investigate the epidemiology of the disease along with the unique clinicopathological and biochemical phenotype associated with vCJD cases. Additionally, this review will examine the impact vCJD has had on public health in the UK and the ongoing concerns raised by this rare group of disorders.

Scrapie at Abattoir: Monitoring, Control, and Differential Diagnosis of Wasting Conditions during Meat Inspection.

Simple SummaryObservation of small ruminants showing differing degrees of leanness or emaciation is a common occurrence at slaughterhouses. Although either condition may result from similar causes, emaciation and cachexia are usually pathological conditions, warranting total condemnation of the carcass during post-mortem inspection. This is done in order to prevent unfit meat from entering the human food chain. Scrapie, a naturally occurring transmissible spongiform encephalopathy in small ruminants, is characterized by loss of body conditioning and a wasting appearance. Since atypical scrapie has been identified as occurring at a low, but very consistent, the prevalence in small ruminant populations, it is advisable to include this disease as a differential diagnosis of wasting conditions detected during meat inspection at the abattoir. Vigilance for detection of putative scrapie in slaughterhouses, and its differential diagnosis from other conditions associated with wasting carcasses, are of paramount importance for post-mortem decisions on the fate of carcasses, offal, as well as animal by-products.Wasting disease in small ruminants is frequently detected at slaughterhouses. The wasting disorder is manifested by the deterioration of the nutritional and physiological state of the animal indicated by thinness, emaciation, and cachexia. Evidence of emaciation and cachexia, alone, are pathological conditions leading to carcass condemnation during an inspection. Several diseases are associated with a wasting condition, including scrapie, pseudotuberculosis, tuberculosis, paratuberculosis, Maedi Visna, and tumor diseases. On the other hand, parasitic diseases, nutrition disorders, exposure or ingestion of toxins, metabolic conditions, inadequate nutrition due to poor teeth, or poor alimentary diet are conditions contributing to poor body condition. Classical and atypical scrapie is naturally occurring transmissible spongiform encephalopathies in small ruminants. The etiological agent for each one is prions. However, each of these scrapie types is epidemiologically, pathologically, and biochemically different. Though atypical scrapie occurs at low incidence, it is consistently prevalent in the small ruminant population. Hence, it is advisable to include differential diagnosis of this disease, from other possibilities, as a cause of wasting conditions detected during meat inspection at the abattoir. This manuscript is a review of the measures in force at the abattoir for scrapie control, focusing on the differential diagnosis of gross lesions related to wasting conditions detected in small ruminants during meat inspection.

Prion Infectivity and PrPBSE in the Peripheral and Central Nervous System of Cattle 8 Months Post Oral BSE Challenge.

After oral exposure of cattle with classical bovine spongiform encephalopathy (C-BSE), the infectious agent ascends from the gut to the central nervous system (CNS) primarily via the autonomic nervous system. However, the timeline of this progression has thus far remained widely undetermined. Previous studies were focused on later time points after oral exposure of animals that were already 4 to 6 months old when challenged. In contrast, in this present study, we have orally inoculated 4 to 6 weeks old unweaned calves with high doses of BSE to identify any possible BSE infectivity and/or PrPBSE in peripheral nervous tissues during the first eight months post-inoculation (mpi). For the detection of BSE infectivity, we used a bovine PrP transgenic mouse bioassay, while PrPBSE depositions were analyzed by immunohistochemistry (IHC) and by protein misfolding cyclic amplification (PMCA). We were able to show that as early as 8 mpi the thoracic spinal cord as well as the parasympathetic nodal ganglion of these animals contained PrPBSE and BSE infectivity. This shows that the centripetal prion spread starts early after challenge at least in this age group, which represents an essential piece of information for the risk assessments for food, feed, and pharmaceutical products produced from young calves.

When beef consumption becomes politicized: Longitudinal change of US beef purchase intention and political values in Korea

This study identified factors affecting the willingness to purchase US beef in South Korea over the decade since the bovine spongiform encephalopathy (BSE) crisis in 2008. Logistic regression analyses were conducted to assess the effects of demographics, fear of BSE, and political propensity on US beef purchase intentions. The survey dataset showed a dramatic increase in willingness to purchase, from 36.9% in 2008 to 76.1% in 2019. Analysis of the datasets identified changes in the effects of the variables over a decade. The analysis indicated that people who perceived a low level of BSE risk, males, and supporters of conservative parties were more likely to buy the US beef. In 2008, the most important determinant of US beef purchase intentions was risk perception. In 2015, after the widespread panic subsided, while there remained effects of perceived BSE risk, it was moderated by political propensity. Personal political ideology was used as a heuristic in the purchasing behavior of those who doubted the safety of US beef. Finally, the data in 2019 showed decreased effects of both risk perception and political propensity, as more than three quarters of respondents stated that they would buy US beef. Although risk can be easily politicized, it does not persist indefinitely.

The Cellular Prion Protein and the Hallmarks of Cancer.

Simple SummaryThe cellular prion protein PrPC is best known for its involvement, under its pathogenic isoform, in a group of neurodegenerative diseases. Notwithstanding, an emerging role for PrPC in various cancer-associated processes has attracted increasing attention over recent years. PrPC is overexpressed in diverse types of solid cancers and has been incriminated in various aspects of cancer biology, most notably proliferation, migration, invasion and metastasis, as well as resistance to cytotoxic agents. This article aims to provide a comprehensive overview of the current knowledge of PrPC with respect to the hallmarks of cancer, a reference framework encompassing the major characteristics of cancer cells.Beyond its causal involvement in a group of neurodegenerative diseases known as Transmissible Spongiform Encephalopathies, the cellular prion protein PrPC is now taking centre stage as an important contributor to cancer progression in various types of solid tumours. The prion cancer research field has progressively expanded in the last few years and has yielded consistent evidence for an involvement of PrPC in cancer cell proliferation, migration and invasion, therapeutic resistance and cancer stem cell properties. Most recent data have uncovered new facets of the biology of PrPC in cancer, ranging from its control on enzymes involved in immune tolerance to its radio-protective activity, by way of promoting angiogenesis. In the present review, we aim to summarise the body of literature dedicated to the study of PrPC in relation to cancer from the perspective of the hallmarks of cancer, the reference framework defined by Hanahan and Weinberg.

Defining the Prion Type of Fatal Familial Insomnia.

Fatal familial insomnia (FFI) belongs to the genetic human transmissible spongiform encephalopathies (TSE), such as genetic Creutzfeldt-Jakob disease (CJD) or Gerstmann-Straeussler-Scheinker syndrome (GSS). Here, we analyzed the properties of the pathological prion protein in six FFI cases by Western blot analysis, a protein aggregate stability assay, and aggregate deposition characteristics visualized with the paraffin-embedded tissue blot. While in all cases the unglycosylated fragment in Western blot analysis shared the same size with sporadic CJD prion type 2, the reticular/synaptic deposition pattern of the prion aggregates resembled the ones found in sporadic CJD type 1 (CJD types according to the Parchi classification from 1999). Regarding the conformational stability against denaturation with GdnHCl, FFI prion aggregates resembled CJD type 1 more than type 2. Our results suggest that the size of the proteinase-K-resistant fragments is not a valid criterion on its own. Additional criteria supplying information about conformational differences or similarities need to be taken into account. FFI may resemble a prion type with its own conformation sharing properties partly with type 1 and type 2 prions.

Loss of prion protein control of glucose metabolism promotes neurodegeneration in model of prion diseases.

Corruption of cellular prion protein (PrPC) function(s) at the plasma membrane of neurons is at the root of prion diseases, such as Creutzfeldt-Jakob disease and its variant in humans, and Bovine Spongiform Encephalopathies, better known as mad cow disease, in cattle. The roles exerted by PrPC, however, remain poorly elucidated. With the perspective to grasp the molecular pathways of neurodegeneration occurring in prion diseases, and to identify therapeutic targets, achieving a better understanding of PrPC roles is a priority. Based on global approaches that compare the proteome and metabolome of the PrPC expressing 1C11 neuronal stem cell line to those of PrPnull-1C11 cells stably repressed for PrPC expression, we here unravel that PrPC contributes to the regulation of the energetic metabolism by orienting cells towards mitochondrial oxidative degradation of glucose. Through its coupling to cAMP/protein kinase A signaling, PrPC tones down the expression of the pyruvate dehydrogenase kinase 4 (PDK4). Such an event favors the transfer of pyruvate into mitochondria and its conversion into acetyl-CoA by the pyruvate dehydrogenase complex and, thereby, limits fatty acids β-oxidation and subsequent onset of oxidative stress conditions. The corruption of PrPC metabolic role by pathogenic prions PrPSc causes in the mouse hippocampus an imbalance between glucose oxidative degradation and fatty acids β-oxidation in a PDK4-dependent manner. The inhibition of PDK4 extends the survival of prion-infected mice, supporting that PrPSc-induced deregulation of PDK4 activity and subsequent metabolic derangements contribute to prion diseases. Our study posits PDK4 as a potential therapeutic target to fight against prion diseases.

The Microscopic Detection of Animal Proteins in Animal Feed Regarding Bovine Spongiform Encephalopathy

Abstract Due to the actuality of spongiform encephalopathies and their proven spreading by means of animal feed containing meat and bone meal, the description and measurement of osteocytic lacunae contributes to more easily distinguish bone fragments in meat and bone meal. Transmissible spongiform encephalopathies (TSEs) have attracted a lot of attention, especially after 1986, when the first case of BSE (bovine spongiform encephalopathy) was detected. Since the outbreak of spongiform encephalopathy (BSE), the use of animal protein including bone meal as an ingredient in animal feed has been controlled by several regulations including Regulation (EC) 999/2001, Regulation (EC) 1774/2002, and Regulation (EC) 1234/2003. The classical microscopic method is the only official method for detecting animal protein in animal feed in the European Union (Commission Regulation (EC) 152/2009). By applying the microscopic method to the animal feed samples, we performed detection in order to determine the presence of animal proteins that originate from mammals and fish. The microscopic analysis of all 421 samples, of which 115 were raw materials for the production of animal feed, 230 were concentrates for ruminant nutrition and 76 were concentrates for non-ruminant nutrition (32 concentrates for laying hens and 44 concentrates for pigs), did not provide positive results, that is, no remains of animal tissues of mammalian origin were found in any specimen. Whereas in 10 out of 32 (31.25%) concentrates intended for non-ruminant nutrition (laying hens), pieces of fish tissue were found. In these samples, we usually detected the presence of fish bones, gills and scales.

Human Prion Disorders: Review of the Current Literature and a Twenty-Year Experience of the National Surveillance Center in the Czech Republic.

Human prion disorders (transmissible spongiform encephalopathies, TSEs) are unique, progressive, and fatal neurodegenerative diseases caused by aggregation of misfolded prion protein in neuronal tissue. Due to the potential transmission, human TSEs are under active surveillance in a majority of countries; in the Czech Republic data are centralized at the National surveillance center (NRL) which has a clinical and a neuropathological subdivision. The aim of our article is to review current knowledge about human TSEs and summarize the experience of active surveillance of human prion diseases in the Czech Republic during the last 20 years. Possible or probable TSEs undergo a mandatory autopsy using a standardized protocol. From 2001 to 2020, 305 cases of sporadic and genetic TSEs including 8 rare cases of Gerstmann–Sträussler–Scheinker syndrome (GSS) were confirmed. Additionally, in the Czech Republic, brain samples from all corneal donors have been tested by the NRL immunology laboratory to increase the safety of corneal transplants since January 2007. All tested 6590 corneal donor brain tissue samples were negative for prion protein deposits. Moreover, the routine use of diagnostic criteria including biomarkers are robust enough, and not even the COVID-19 pandemic has negatively impacted TSEs surveillance in the Czech Republic.

Prion diseases, always a threat?

Prion disease is caused by prion which was identified as a causative factor of transmissible spongiform encephalopathy such as Creutzfeldt-Jakob disease (CJD) and means proteineaceous infectious particle. Prion diseases are devastating neurodegenerative disorders of human and many animals including sheep, cows, deer, cats and camels. CJD presents usually as a rapidly progressive dementia with other symptoms inevitably resulting in death often in months with no available therapy. Like other neurodegenerative diseases, prion diseases are classified into sporadic and genetic forms. In addition, there is the third category of environmentally acquired form. This type includes kuru and iatrogenic CJD due to human dura mater grafts or human pituitary derived hormones as well as variant CJD transmitted through food contaminated with prion of bovine spongiform encephalopathy (BSE). BSE and variant CJD has been almost controlled but chronic wasting disease, prion disease of deer, is spreading widely in North America and South Korea and recently in northern Europe. Recently Aß, α-synuclein and other proteins related to Alzheimer's, Parkinson's and other diseases were reported to have prion features such as transmission to animals. Aß transmission to human was suggested in iatrogenic CJD cases as well as in cerebral amyloid angiopathy cases with cerebral bleeding long after childhood neurosurgery with or without cadaveric dura. These findings indicate prion diseases due to various prions, namely various transmissible proteins appear to be a threat particularly in this longevity society. To overcome prion diseases is one of the top priority in our society.

The possibilities of alternative protein use in animal nutrition

The Food and Agriculture Organization (FAO) predicts there will not be enough food for human and animal nutrition until 2050. Global demand for animal protein for human consumption is increasing, and this consequently increases the price of these ingredients. This will open several challenges to provide enough animal feed. In the European Union, the use of processed animal proteins in pig and poultry diets is prohibited due to the bovine spongiform encephalopathy (BSE) legislation, while globally, the land availability for soy cultivation is limited. The European food market is dependent on huge import of soybean, which is the main source of valuable proteins and one of the main ingredients in feeds. Feed ingredients must not contain antinutritive factors that would adversely affect animal production and must have an acceptable price. Some of the alternative plant sources of protein are fava beans, peas, lentils, hemp, different grain seeds, etc. To find alternative sources of protein of animal origin scientists are increasingly investigating the use of worm, snail or grasshopper meals and also marine organisms, usually algae, shells or starfish. Single cell proteins are a specific kind of protein from different microbial sources, including microalgae, yeast, fungi, and bacteria.