Hypotheses for the origin and spread of BSE

An attempt is made to put forward the arguments for and against each of the hypotheses but the space needed for this may be too great and hence further contacts are given. If you are unhappy with any of them or feel that specific points have not been put forward then please e-mail the editor here and we will try to include your ideas if they are felt adequate. The arguments as to the infectious agent being a virus, a virino or a peptide can be found elsewhere. Other well known hypotheses are not included here.

Subjects:

Horn Report (July 2001) (www.maff.gov.uk/animalh/bse/bseorigin.pdf)

Summary
Individual arguments
Major 3 arguments seen as reasonable

Scrapie the cause
BSE spontaneously appears due to a genetic abnormality in cattle
A TSE is transferred from another species

An editorial of the Horne report

Current hypotheses

BSE derived from scrapie
BSE is a rare sporadic disease of cattle
BSE derived from CJD
Organophosphorus insecticides involved
Knackers yard greaves involved in transmission
Bacterial toxicosis causes BSE
BSE is a lysosomal storage disease
Horizontal BSE transmission through the eye
A list of feed changes that may be involved
BSE is an autoimmune disease
BSE transmission is via a campylobacter-like organism
Alkaloidal glycosidase inhibitors cause PrPc structure change
Smarden spill caused toxic induction of initial BSE outbreak
Thioldisulphide interchange chemistry caused PrP configuration changes
Bovine pituitary hormone use caused initial spread of disease (also see Dr Parry's discussion of this)
Oligonucleotide involvement in transmission agent
BSE cases seen are vertically transmitted but a much higher proportion of herd are asymptomatic
A range of trace metals may be involved in BSE symptoms and pathology.
BSE controlled by prostaglandin
BSE is the clinical sign seen when a chromosomal virus is expressed
Ubiquitin is important in the formation of TSE agent
A list of interesting, rather crafty ideas
Thiomersal as a preservative in vaccines induces PrP change
BSE type illness will result when it is 'worthwhile' in evolutionary terms for a specific protein multiplication
Retroviral origin of prion disease
Waste water sludge involved in BSE spread
Cross linked dietary proteins involved
Phonons are involved in prion formation
MBM increases in 1980 (Huge increase in MBM use causing BSE rapid rise)
d-aminoacids alter the PrP structure
The endogenous origins of spongiform encephalopathy
PrPsc is an intermediate form of PrPc.

Discussion
Current difficult argument:

The Horn Report. The Origin of BSE in the UK

A review of the Summary that is given to the press

1. Unlikely that specific chemicals are associated with the development of the disease. This includes with the idea that organophosphorus insecticides were involved.

2. Unlikely that many aspects involved in the environment were the origin but may have caused the explosion of the disease (e.g. inoculation of hormones made from bovine pituitaries). This also includes the effect of the feeding of MBM made from infected cattle to further cattle.

3. Unlikely that the import of ungulates is involved with the development of the epidemic.

4. Many hypotheses are not discussed.

5. Scrapie was seen as the most likely sourcealthough the report starts by saying unmodified scrapie can no longer be excluded. The large excess of sheep over cattle in the UK (as opposed to other countries) would mean that UK would be most at risk of the disease passing to cattle. The feeding of cattle early in their lifespan with MBM in the UK may mean the development of the disease here.

6. BSE could be a result of a somatic mutation in a single cattle's genome but they feel this is unlikely. In the end it was considered that BSE was 'one hitherto undescribed agent in sheep which possibly acquires new characteristics on recycline in cows'.

In the end the report gives the impression that scrapie as a source of the disease should be taken as the most likely and as such research should go into avoiding this in future.

It is important to read the full Horn Committee Report not just the summary because the full Report gives a more balanced view. It is important to remember that these are all hypotheses and likely to remain so until the agents are better understood. On the other hand hypotheses must be explored to try to prevent a recurrence of events similar to the BSE outbreak. Notably the summary laves with:

Individual arguments assessed by the Horn Report

1. OP insecticides are thought of as being exceedingly unlikely to be involved.
2. An autoimmune condition also thought exceedingly unlikely.
3. A viral condition that managed to spread as an epidemiological factor was seen as unlikley due to the rapid growth of the disease. The committee decided that the most likely was that the prion seemed the most reasonable agent and that it did not start as an epidemic in 1980 but rather around the end of the 1960s or early 1970s.
4. The epidemic being due to the change in the manufacturing process for MBM that took place in the 1970s. This was thought to be unlikley but possibly associated with the development of the epidemic. They felt that although the change in the level of infectivity in the MBM may only have risen 10 fold this may have been adequate to cause the epidemic. See Horn editorial.
5. Specific chemicals were involved in the starting of the epidemic (this is mainly referring to the chemicals that were found associated with the early cases in Kent and the place where the first case of vCJD had lived) were felt to be unsubstantiated at this time. The report did not, however attempt to state it was wrong as they did not have enough information.
6. Heavy metal involvement was felt to be unlikely.
7. Many hypotheses were not discussed as being 'off the wall'.
8. Ungulates were felt to have nothing to do with BSE. The import of them in the early 1980s that took place and was reported in the Independent in 1997 was felt to have taken place too late to be involved.
9. Pituitary hormone injection, although known to take place for many years had been increased in the 1970s but the committee felt that this could only really be thought of as a potential part explanation for the rapid expansion of the disease at that time. (They also considered oxytocin injection which had been used for a long time before FSH).

Major three arguments are thought to be difficult to argue against

1. Scrapie was the cause of BSE. It was felt that there was a large number of sheep in the UK and an endemic amount of scrapie. The level of this disease was unknown but had been considered to be from exceedingly low (some farmers saying that they had never seen a case) to worryingly high (occasional reports of many cases in the same herd). It was felt that, as in the UK there was a relatively high number of sheep per cow then this may explain why BSE appeared in UK rather than in other countries endemic with the disease (from Wilesmith's work, published to the USDA in 1991). There are arguments against this: see Horn editorial. However, the committee felt that this was the most likely in that no cases of spontaneous BSE had been reported in other countries, specifically in the USA where a large number of cattle are being tested for BSE. It was shown that cattle in the UK are fed with MBM when extremely young and, as it has been shown (but not published by the epidemiology group at VLA) that infection takes place early in the animal's lifespan it was considered that this may have been a major cause. Also, cattle that are not suckler reared (i.e. were fed artificial milk and meal early on) were much more likely to develop BSE.

2. That BSE was derived from a spontaneous genetic mutation of a single animal. Familial disease in humans is associated with mutations in the PrP genome, generally at specific sites and genetic changes in mouse PrP genes can make them more or less open to infection. The various mutations give rise to different clinical forms of the disease. The Horn Committee felt that, as no cases of BSE (even as a rare condition) have been found in US cattle being tested currently in fallen animals, the condition should not be assumed to be the cause.

3. A TSE from ungulates. This was felt to be unlikely as endemic TSE in ungulates in the wild was unknown and the import may have been at the wrong time even though bone meal was imported in the 1970s.

Horn Editorial

Some of the arguments in the Horn Committee Report that may be difficult to be certain of:

That the change in the rendering process of MBM was involved. The problem for this was that several of the rendering works changed their methods quite early in the 1970s and, as MBM is produced in bags, the early plants would have produced infective material early on. i.e. little would have waited until a certain percentage of the plants was changed to the new methods. The figure that Horn gives is inadequate in fact to show any difference between the different rendering methods. This is because the dilution of infected tissue is by ten fold at each step and as a result the two methods were only one dilution apart: inadequate in current methods to show any difference.
That scrapie was the source of BSE. It was clear quickly that BSE was not the same condition as found in sheep, and that it appeared to affect different parts of the brain. Also, inoculation into mice produced a different pathological change in mice from that found when BSE was injected. Scrapie used for inoculation studies appears to infect different ranges of animals. Also it was felt that the world-wide distribution of cattle of a few breeds would have meant that UK would not have been the first to develop the epidemic unless there was some other cause apart from familial/spontaneous genetic change in a single animal. From all these findings it is clear that scrapie is not BSE and hence BSE could only really take place as a result of scrapie if a specificaly unknown scrapie strain was involved. It should be noted that a scrapie mutation in sheep to a new form that would infect cattle easily would not depend on the ratio of sheep to cattle at all. MBM is made now in a flow-through process ending up in bags. Therefore, for a single infected sheep to cause the contamination of a bag eaten by cattle, it would not depend on the ratio of sheep to cattle per se but the total number of sheep in a country and the proprtion of MBM bags fed to cattle. When the mathematics is done on this it would seem that the USA was more likely than the UK to have the first case of BSE. i.e. Horn Committee's argument is not valid (as was pointed out to Wilesmith at the time). One of the most obvious arguments is that if there had been a scrapie strain of BSE, then it is not clear why there had not been earlier BSE epidemics in cattle and in other countries.
That genetic BSE was not the most likely cause of the epidemic. What was not clear from its report is that the committee was aware that it was not necessary for the cattle to be genetically modified to cause them to develop spontaneous disease, but could have been merely made more open to infection from sheep scrapie. Taking that as possible may actually explain why there may be minimal spontaneous BSE in the USA. The idea put forward that cattle that are reared by suckling were less likely to develop BSE is inadequate in that some sucklers certainly do develop the disease with a similar age distribution of disease as the non-sucklers. This was investigated in Northern Ireland where most of the cattle are beef sucklers.
Possible cow origin. The prion hypothesis as stated by S Prusiner does include somatic mutation or spontatneous change of protein as possible sources of sporadic disease. Sporadic disease does have to be explained as part of the prion hypothesis if that is going to be the basis of the explanation of the nature of TSEs.
That UK was the first country with BSE was due to scrapie and early MBM in diet. It is certainly true that UK introduction of MBM to a calf's diet is exceedingly early in that it is advertised to farmers as being good for them. It is also true that cattle become infected exceedingly early (Dealler SF. British Food Journal 2001;103:264-280). This is probably due to the uptake from the bovine gut of large molecules for a period after birth. The effect is gradually lost after the first month and is hardly seen at all in humans. Cattle had, however been fed early with MBM for a relatively long time, and so it is not clear why the disease should have appeared when it did.
BSE when inoculated into further animals did not lose the its strain nature. The Horn Committee feels that BSE was from scrapie after it had been altered by cycles of being turned into bone meal. However, this is uncertain as the BSE does not
That ungulates were not associated with the disease. The argument given by the Horn Committee is that, as there is no evidence it should not be taken as likely. However, as we have found with many other factors of BSE, just because we dont have the evidence does not mean that it is not going to be found or that we just have not looked adequately. This same factor applies to many of the decisions of the committee concerning other potential hypotheses.
The decision that scrapie is the most likely source of BSE may well give rise to the further development of genetically modified 'null' sheep (i.e. sheep not carrying the PrP gene). This would be exceedingly expensive and would involve the loss of many breeding flocks. If in the future it turns out that this was an error it would be too late. However, the report makes it clear that they simply do not know where BSE came from (indeed they are quite open about this), and as such other courses of action may be worthwhile.
Many of the hypotheses were not mentioned whatever. Tony Austen's work suggesting relatively easy infection early in the lifetime of the animal and that this may not be a prion at all was not discussed apparently. Nor were many of the hypotheses in this document. It should be said that many of the authors were not contacted.

Current hypotheses

In this document I am not going to discuss greatly the arguments as to whether the agent of disease is a virus, virion, prion or mycoplasma as have been fully discussed elsewhere. Some aspects of the discussion here are, however important to that argument, however (e.g. hypothesis 32 contains information showing that prions are not possible without other chemical aspects)

1. BSE derived from scrapie and this was present in bovine feed as a result of changed in the manufacture processes for MBM.

Pro:

1. Cattle could be infected with scrapie by experiment.
2. Epidemiology did not start as a single case and followed by multiple peaks.

Anti:

1. BSE was not the same strain of TSE as any scrapie investigated previously.
2. When scrapie inoculated into cows they got a different form of illness.
3. No fall in incubation period was seen.
4. BSE did not have the same range of infectivity as scrapie.
5. No apparent increase in scrapie during the perioddespite large amounts of MBM fed to sheep.
6. Areas where BSE started were not particularly sheep areas (could be explained by movement of sheep carcases to renderers).
7. No clear alteration in infectivity of MBM using solvent extraction methods.
8. No alteration in infectivity expected in MBM due to continuous rather than batch rendering.
9. Epidemiology and clinical nature of disease suggests that all BSE derived originally from a single point source.i.e. not from many different strains of scrapie.

2. BSE existed in the country as a rare disease in cattle and the epidemic was due simply to this becoming established in the MBM feed chain.

Pro:

1. No fall in incubation period was seen early in the epidemic
2. This would not require the first case to have taken place in 1981 but could have been earlier.
3. No necessity for rendering processes to be involved (no evidence that they they were).
4. Areas where BSE started were not particularly sheep areas (could be explained by movement of sheep carcases to renderers).
5. BSE has a specific range of infectivity (separate from scrapie apparently).
6. No increase in sheep disease was necessarily going to be seen.
7. Outbreak of TME in Stetsonville possibly associated with a TSE in a cow.
8. Reports from veterinary surgeons that they feel they had seen cases of BSE before the epidemic simply as rare conditions in cattle.
9. Work by Collinge and by Bruce indicates that BSE is not similar to scrapie of the strains that they have available.
10. Epidemiology and clinical nature of disease suggests that all BSE derived originally from a single point source. i.e. not from many different strains of scrapie.

Anti:

1. The index BSE case would be expected to give rise to BSE cases that were most infective between 3-6 years later and those would be expected to give rise to a second peak 3-6 years after that (each peak broader but 10-100 times higher (Dealler, Donnelly). As such it might be expected to see a specific shape to the epidemic curve. No such shape was seen. This is a quite difficult problem to avoid.
2. Unclear why other countries using similar agricultural methods did not get a similar outbread of disease.
3. If it came from a single animal with disease then this index case may have been in the early 1970s or 1960s and could not have been associated with rendering methods. No evidence for this.

3. BSE was derived from CJD.

Pro:

1. Antibodies were raised for the radioimmuno assays for various human pituitary hormones by inoculating the hormones into animals. The animals would have been destroyed at the end of their useful lifespan.The most impure hormones used for inoculation would have been in the 1960s.
2. Body destruction following murder has been suggested to have been by rendering.
3. The spread of human body ashes on land.
4. No reqirement for the initial inoculation of cattle to have taken place in 1980. As such it would not be likely to see a series of peaks before the main epidemic rises.
5. Poor evidence that BSE derived from scrapie and no certainty that BSE appeared in UK as a sporadic infection

Anti:

1. Work by Collinge and by Bruce showed BSE not to be similar to CJD of strains that are known but rather to be similar to nvCJD, which was unknown prior to BSE. (but some aspects of strain may change when transferred from one species to another)

4. Organophosphorus pesticide causing BSE.

Pro:

1. Similar symptoms to OP toxicity
2. Changes in OPs during epidemic period
3. Same OPs used in specific countries with BSE
4. Warble fly treatment at a specific part of the year and this could explain why BSE is more common in cattle born at specific times.
5. Low rate of BSE in cattle of organic farms that did not use OP.

Anti:

1. Epidemiology of BSE does not fit the usage of OP
2. OPs used in specific groups whereas as a toxicity it would be expected not to have a peak at 4-6 yrs.
3. Cattle claimed not to have had any OP exposure develop BSE
4. OPs were in use before BSE appeared.
5. No specific OP changes took place in 1988 when the peak was reached in BSE.

lizziedrip@ntlworld.com

1) BSE started in 1985
2) The change over from OC to OP sheep dips began on Jan 1st 1985
3) Diazinon is a known nerve toxin
4) This chemical alone or in combination with other OP's could be responsible for BSE in UK cattle. It predicts for example the rise and fall of BSE.
Jan 1st 1985 was the first date UK adopted diazinon. It was trialled before obviously - so where where the trials done? What was the effect on the farm animals involved? Cattle associated with the sheep.
The correlation with disposal and status of herds.
Organic farms do not get BSE.
Sheep dipping was reduced to one dip a year in 1989.
In 1992 it was no longer compulsory.
In 2000 it was banned.
All these effects have had the required effect on BSE cases.
Other countries using OP's have had some cases of cows with brain problems. Not however BSE.

Purdey's web site

5. Knackers yards also melt down tissue and sell greaves, often with a high fat content to renderers. This has taken place for many years and the output from knackers yards does not seem to have been fully investigated. A particular proponent of this was a member of the industry (Doug Anderson). He looked at the changes in the way in which various knacker melters lost revenue as a result of the solvent extractors and he explained why a high titre of infectivity would be derived directly from these sources than through renderers.
6. Bacterial toxicosis. This is a complex hypothesis put forward by Tom Stockdale (21 Castle Douglas Rd, Dumfries DG2 7PA) and involves the carriage of bacterial toxins to brain by a glycoprotein receptor corresponding to PrPc. This would result from the presence in the gut of abnormal proteins (e.g. fish).
7. BSE disease associated with a lysosomal storage type disease. This is the complex hypothesis put forward by Kevin O'Donnell from Edinburgh University (odonnell@embra.compulink.co.uk). In this he notes that the PrPsc form of the prion protein builds up partly because it cannot be broken down by lysosomes. He suggests that sporadic cases and familial cases may actually not be due to PrP alterations but possibly because the lysosomes fail to destroy them and they then build up as a crystalloid structure. (Jolly RD, Walkley SU. Lysosomal storage diseases of animals: an essay in comparative pathology. Vet Pathol 1997;527-48) The narrow genetic difference among dairy cattle in the UK might be involved in this. See the full theory under lysosomal hypothesis. (NB: I think he is changing his web site address so you may have to find other ways to find it).
8. It has been suggested that insects may have permitted thetransmission of prion infection horizontally from the eye of one animal to the eye of another. (Vince Lisa, 284 Birchwood Rd, Medford NY. 11763, USA). The spread by mosquitoes has also been suggested but probably inadequate amounts of blood spread are present (Dean Goins, N. Carolina).
9. Other changes in animal feed took place over the same period in 1980-81.

The large increase in the growing of rape seed plants and the change in the colour of the countryside as a result. Rape contains a high selenium content apparently and this has been suggested as a neuro toxin that might affect a prion infection. Rape oil is extracted and the remaining material is used for meal. It would also lead to a sudden drop in selenium in diet when other diets were introduced. It is this sudden decrease in the availability of selenium that is considered to be a possible cause.
The bringing in of UDP feeding, which involved feeding cattle with much large amounts of protein than the rumen could handle and hence led to the appearance in the jejunum of intact protein. It was decided that the overload of rumen bacterial action would lead to much greater amounts of amino acids being available for milk production. The calculation for the protein content for the feed was difficult and really only done by feed manufacturers, who used this to produce much higher protein feeds and promise greater milk output from a single cow. This has been fully explained by Dr. Maddocks.
The use of black polythene plastic bags for holding offal for rendering. These were often simply thrown into the rendering plant mix and the offal not removed. This was simply because in the rendering system, the material was cut into small fragments for a continuous process and the bags disappeared. It was suggested that the bags, being of polythene would act as a hydrophobic surface and hence protect prions.
BSE in cattle may have arisen from a rare disease which affected the brain and spinal cord of horses. This disease is referenced in old books as one of a group of ailments known as staggers. About 50 years ago, the disease was 'lost', possibly because its incidence decreased, and all references to staggers are now assumed to relate to alkaloidal poisoning, most commonly by ragwort species (Senecio jacobea and Senecio vulgaris) in the UK countryside. There is no cure for staggers caused by alkaloidal poisoning. The symptoms occur when liver damage has reached a critical and irreversible level. However, the 'lost' disease also referred to as staggers was considered to be curable, and one cure was minute doses of ragwort. Giving more ragwort to an animal already suffering from ragwort poisoning could only hasten its death, but it is just possible that the specific alkaloids in ragwort could have a beneficial effect in BSE in very small doses. It is possible that infected horsemeat was introduced into cattle feed during the 1980s, and that nvCJD may be transmitted directly from horses to humans, through vectors such as ticks or faeces. From press reports, at least some nvCJD victims had links with horses. This is a complex issue and if you need further information please contact jan.williams@fibonacci.co.uk.
Molybdenum toxicity Possibly associated with the lysosomal storage type syndrome of Kevin O Donnell. More information from Dea Shelton at sheltond@pacbell.net
Importation of tropical bones. The value of the pound at the beginning of the 1980s was extremely high and the importation of protein for animal food was felt to be worthwhile. It has been claimed (Independent 1997) that the disease was in fact prevalent in one of the animals from which the bones were from e.g. gazelles.
Shortage of copper in bovine diet. The change on bovine diet due to alterations in the type of source (contact Murray McBride). This may explain why the disease started when it did in 1980 as it was then that the diet changes took place. Also there have been many indications that copper deficiency gives rise to a spongiform encephalopathy although no sign has been present as to why this is present. The suggestion is that possibly either copper deficiency sparked the epidemic by making animals sensitive to a transferred disease or it is more involved in the ongoing disease process. The wheat plant [barley,flax] is highly ineffective at picking up copper from soils low in this mineral.When deficiency occurs we get a host of disease symtoms [wilting,weak stems, melanosis, seed failure,thin seed, ergot to name a few]. When adequate copper is supplied to the wheat plant all of these symtoms vanish. High levels of Zn, Mn,P,and N will all interfere with copper metabolism. Several common herbicides will drastically enhance copper deficiency symptoms in wheat eg.fenoxaprop-p-ethyl. Seventy percent or more North american cattle at slaughter have been shown to be copper deficient. Copper deficiency when combined with high levels of molibdenum in the diet results in cattle death even though they may be fed supplemental copper mineral I think that all of these copper interrelationships need to be thoroughly checked out considering the important role that copper plays in prion formation.ieuan.evans@gov.ab.ca

10. Auto-immune reaction causing BSE brain damage. This is partly described by J Axelrad in Medical Hypotheses 1998;50:259-64 (0044 1455 292738) and by Alan Ebringer in various publications in: see Medline.

The appearance of the brain similar to auto immune disease
Chronic process
Antibodies to certain bacteria (acinetobacters) higher in cattle with BSE than in cattle without BSE. These bugs produce proteins that cross react antigenically with PrP
Minor fall after feed ban.

Anti.

Epidemiology does not fit with autoimmune disease.
Acinetobacters are not new and are present in all countries of the world.
Peak at age 4-6 yrs and incubation period relatively steady. But no reason why this should be so for auto-antibody disease.
Transmissibility of disease by inoculation
Fall in the disease when feed ban introduced.
Some farms that do not use certain feeds or OPs do not also have BSE but they would be expected to have acinetobacters similar to other farms.
No antibodies to PrP found in blood of animals with BSE or any TSE
Inflammation at the plaque site is present but is not in an auto immune fasion.
No reason why a prion form to a PrP protein should be involved in any way
No experimental data concerning the inoculation of acinetobacters and the presence of antibodies being associated with the development of a TSE that is then transmissible.
TSE can be transmitted from one animal to another by inoculation of purified material that could not contain bacteria.
No response to antibiotics: even in animals given heavy doses from long before symptoms appear.
Animals that cannot produce any antibodies whatever still develop TSE when inoculated with material.
Animals that cannot produce any antibodies or T-cells still can develop TSEs
Alterations using chemicals of the immune system affect the incubation period only marginally or the development of disease (e.g. steroids, anti-cancer drugs).
Disease is modified by amphotericin B, which is not thought to alter the immune system at all.
Infection can be demonstrated in vitro in which no immune system is present whatever.

11. Transmission of the organism in a campylobacter-like organism among young cattle. This initially seems implausible but the work done by Done, who indicated that an organism that could be cultured on agar could be shown to be resistant to all the factors that seemed to similar to prions. i.e. heat, light, radiation etc. He also showed that it could be transmitted. His reasearch has been little noticed except by one group that suggest that the BSE agent was transmitted in the same way as bovine gut flora in advance of the rumen bacterial flora (Austen, T) or as a campylobacter-like organism between animals (Roland Heynkes on 0241932072-0001@t-online.de) and this idea is fully put forward on Heynkes' personal web site. The research into it seems to have been refused by MAFF. This sort of hypothesis can explain the epidemiology of the disease quite well and the reasons found that cattle born within a few days of each other seem to share the same risk of BSE on a particular farm. It should be brought in at this point that the amazing work by Bastian concerning the possibility that there is an agent for TSEs that are spiroplasma (see Ed Gehrman's section) has been largely ignored in the literature of BSE. Ed Gehrman has put forward this repeatedly on the net but little has got into the literature. (egehrman@psln.com). (It should be noticed that the data lower down on this document showing that infection took place in cattle exceedingly early in the lifetime of the cattle does indeed suggest some other much more infectious item being invovled with the feed than a prion)
12. Alteration of PrP glycosylations by alkaloidal glycosidase inhibitors. These are small, sugar-like compounds that prevent the breakdown of carbohydrate chains that are on the surface of proteins. The effect they have mainly is to cause all the chains to be the same. i.e. when the AGIs are not present, the PrP made by one cell will carry different carbohydrate chains from the PrP made by another. When the AGI is added the carbohydrates become the same. Now, one of the things that is required for the transmission of PrPsc infection may well be that the carbohydrate chains are identical on the infecting PrPsc and on the PrPc that is changing into its form. This can be made certain of by AGIs. Remember, at the beginning of the 1980s there was a huge increase in the production of foods from potatoes, which contain large amounts of AGI (Nash et al) and remember that animals were fed with the potato fractions that were not needed. Also remember that the sweet potato also contains a lot of them and that the kuru affected tribe in New Guinea would have eaten large amounts. (for a full explanation: Dealler 07625 107520. Further work taking place currently at the University of London).
13. Smarden spill. The manufacture of methyl bromide and fluoracetemide from the Rentokil factory at Smarden in Kent gave rise to chemical release, and groundwater contamination reaching peak in 1963. Cattle that died as a result of chemical poisoning were sent to knackers and renderers in the 1960s. The BSE epidemic first appeared 5 miles from this site. Williams, John, who is an independent researcher into epidemiology of nvCJD looked hard into this and presented the data to the Phillips Inquiry he is contacted on 0049 6221 64006. Mobile phone 07771 622076
14. Chemical interactions that cause alteration in PrP shape (Abstract from paper: Barry Willis, THIOL-DISULFIDE INTERCHANGE THE KEY TO CONFORMATIONAL CHANGE OF PRION PROTEIN?) Prion protein is involved in a group of neuro-degenerative diseases. The conversion of the soluble cellular prion protein into the pathogenic insoluble isoform is accompanied by a decrease in a-helical structure and an increase in the b-pleated sheet content which aggregate into amyloid fibrils. The conversion of a-helices of prion to the b-pleated sheets is most likely to result from the reduction of stability of the a-helices relative to the b-pleated sheet. Such a mechanism of stability reduction exists due to the presence of the disulfide bond between two a-helical components of the cellular prion protein and their ability to undergo thiol-disulfide interchange. This can be reached directly on the link http://www.ozemail.com.au/~tkwillis/prion/ . If, however this link has stopped as the author said it would, you can get to him on willisbp@tig.com.au. This work has now been published as Feuchelman M, Willis, BK. 'Thiol-disulphide interchange a potential key to sonformational change associated with amyloid fibril formation.' J Theor Biol. 2000;206(2):313-5.

use of bovine pituitary hormones

http://www.bse.org.uk/doc/stat467.doc

suplementary statement

appendices

Dr Parry's information showing that inoculated hormones were present at the time and that their use in cattle would fit the epidemiology of the BSE epidemic to some degree

16. Small DNA chain associated enters host genome and is protected by protein when multiplied According to the hypothesis the causer of the disease is oligonucleoprotein, that is situated in the genome of the host. In fact,the causer is a nucleosome which is constucted of oliginucleotide and histones. It differs from nucleosome by the succession of nucleotides and this very difference is the cause of the pathology. That infectious oligonucleoprotein integrates into the construction of the host genome. After being integrated into the host genome, it makes changes in the construction of the gene and if it is a unique gene, then the primary construction of the corresponding protein changes. The gene mutation caused by the integration of the infectious oligonucleoprotein is a reason for an anomaly constructed enzyme production. The mutation of the given gene may occur spontaneously too as well as the mutation may be inherited. The causer of the disease is not inactivated by DNAse because DNAse ruins DNP/P-protein/ up to oligonucleoprotein,which is resistant. According to the hypothesis the causer is the stated above oligonucleoprotein, which is resistant to the DNAse inactivising influence and vice versa, after the influence of DNAse the causer separates itself from the genome and may produce infection.The DNAse cannot ruin the oligonucleoprotein, because the molecules of the histones protect it. But the causer may be inactivated by PROTEase,because the PROTEAse destroys histones and they don't protect anymore the oligonucleotide of the destruction.Furthermore ,prionsappear to remain infectious een after being exposed to treatments that destroy nucleic acids. Besides,the fact that in PH=10 condition the causer is inactivated, it also agrees whit the hypothesis. As the histones are alkaline proteins, then in PH=10 condition they are deproteinated/they lose H+ ion/,they lose the positive charge, resulting the lost of ionic contact between negative charges of phosphates of nucleotid and positive charges of the histones. That is histones separate themselves from oligonucleotides. The hypothesis also gives explanation to the question how the multiplations of the causer takes place. Antibodies don't produce to oligonucleoproteins, because last one have small sizes. (This hypothesis requires further information to justify various interactions with PrP and to explain the many scientific findings with the disease - Editor. It was put forward by YERVAND KARAPETYAN at yervand@mailcity.com)
17. High proportion of BSE cases vertically transmitted. Some reason was needed to work out why cattle seemed to become infected before 18 months of age. Statistically it seems that they are either infected between 6 months and 18 months (Fergusson et al) or, to a large degree before or shortly after birth. As there seems to be little reason why 6-18 months should be the reason at all, it has been considered that almost all the cases that we see are in fact infected from their mother. For some reason the proportion of cattle in any herd that develop BSE rises quickly to around 15% but uncommonly gets any further. Because of this the epidemic in case numbers that is seen is not so much due to an increase in cases in herds but an increase in the number of herds that are affected. The question arises as to why only 15% should be affected and this is unclear; why not 100%? Surely cattle would be more likley to be exposed to BSE in their milking life when they were fed larger quantities of MBM...but it is not these cattle that seem to develop any disease but rather ones exposed early in their life. The hypothesis suggests that when a herd is infected, in fact it is a very large proportion that do. However they would develop symptoms (if at all) late in their life (perhaps aged 17) i.e. long after slaughter. As such the proportion that we see developing symptoms are the offspring of those mothers and that the VT rate is 15%. The epidemiology for this is not unreasonable but involved Ro factors dropping long before the feed ban was introduced. Fergusson's work at Oxford suggests that the Ro did in fact drop in association with the feed ban although the refusal of MAFF to permit any other group but this one to work on the data makes this difficult to argue. (My own findings agree with Furgusson in this but until around 1996 it did seem reasonable - Ed.)
18. A range of trace metals may be involved in BSE symptoms and pathology. This was put forward by Dr. Jane Karlsson and goes through how it is not really surprising that certain symptoms are involved in UK animals and perhaps may be particulary susceptible to BSE in that neurotoxic heavy metals and interactions between them are repeatedly discussed as being of importance in the bovine diet of the UK. Full discussion of these ideas. The Purdey's went over the possibility of the excess of trace metals and explain this in their web site. Have a look at the Purdey's web site which involves both the heavy metal and OP hypotheses.
19. BSE is associated with prostaglandin activity. This follows the ideas of Arne N Gjorgov, who published an article 'Prevention and eradication of the BSE: A solicited response and proposal' Macedonian Vet Rev. 1996;25:97-101. It follows the fatal neurological condition of pseudopregnant mice following sterile mating whereas none of the controls that received prostaglandins developed the condition. The hypothesis is that this kind of disease may be transferred through a mating system in the mice and prevented by prostaglandins. It is suggested that prostaglandins may be a prophylactic factor in BSE.
20. BSE is seen when a chromosomal virus is expressed. My view is that outbreaks of actual disease occur when an otherwise silent C-DNA resulting from initial accidentlal retrotransfection of RNA semi-virus is activated into re-transcription. The question I think is why so many cows and people do NOT get BSE/CJD once infected and whether this happy state can be prolonged throughout life. Part of my hypothesis therefore is that "environmental" affronts whether by atmosphere (insecticides) of food may activate "disease" from benign latency. Queniborough is the next village to Syston where Asmer Flower Seeds greenhouses were overcrowded with hanging insecticide impregnated yellow terrors. How many at Queniborough worked at Syston? Was there or is there any intensive horticultural glasshouse nursery near the Doncaster street where the two new occurrences come from. Did such nurseries if they exist also used toxic hanging strips at high intensity? This idea of course also relates to sheep dips etc. The author has specific reasons why this should be so and how the PrP becomes changed as a result. Some of this relates to the ability to immunise an animal with one scrapie strain against another. Contact: Colin Leakey at clal@zoom.co.uk. The idea will explain a number of things such as the rapid spread of BSE in the UK but the low percentage of cattle that actually die per herd.
21. Ubiquitin as a significant factor . The relationship of ubiquitin metabolism to prion catabolism may well be overlooked. When prions are changed by variant prions(vCJD) the basic amino acid sequence is unchanged.The change is one of a conformational change.I suspect that this rotation may cover thie ubiquitin binding site.This may even cover the RING site ,critical for ubiquitinization of affected proteins.This mechanism would be in line with the lack of immune reaction seen in these prion protein disorders. I would be happy to discuss this molecular hypothesis with interested parties. Roger Orth MD R1ORTH@AOL.com
22. A list of interesting, rather crafty ideas but without any proof or argument.

Mink escapes in the UK? (Nick Skinner)
Import of tropical ungulates? (Alan Dickinson, Charles Arthur)
BSE came from outerspace? UK feeds its cattle outside in the winter so makes us more open to infection in this way.
BSE is associated with the eating of Lolium temulentum, a rye type grass that is known to cause neurological damage in sheep. Although it may not cause the infective form of the condition, it may be associated with the symptomatics (Rik Wade, Rik@valcon.fsnet.co.uk)
Psychological changes making the animal or person more open to prion disease? Jean Dore has investigated the effect of psychology on the development of long term illness such as this. Although there is no current evidence that TSEs could act in the same way, he feels that this should be understood and has produced a document available through himself at pro.anima@wanadoo.fr into this. The message was passed on to me by Claud Reiss.
The presence of D amino acids (i.e. not the L-amino acids produced and found in normal mammalian proteins) in the bacterial diet of the cattle being involved. from Dr Klaus-J Seelig.

23. Thiomersal damage to PrP. Thiomersal, a presative used in vaccines that are given to calves may cause changes, it is felt, to PrP. The chemical changes that thiomersal does produce are really quite widely seen as is shown by the author,Peter Wevers www.altcorp.com/SlideShows/Thimerosal/sld024.htm. Now, so far I have not been able to contact him to discuss the subject fully but the web site does go over how the interaction with thiomersal may make major differences to SH groups on proteins. It structure is on www.altcorp.com/SlideShows/Thimerosal/sld003.htm.
24. BSE type illness will result when it is 'worthwhile' in evolutionary terms for a specific protein multiplication. It is suggested (PSRK Sastry TSEs and the 'rogue shareholder protein' hypothesis, Medical Hypoth 2000;54:186-8) that because the prion may cause the multiplication of its own type, it makes itself become more important for production. As a result, an infectious form that depends on a long incubation period would result.
25. Retroviral origin of prion disease This suggests how a murine leukaemia is associated with a slow retrovirus and how this causes a spongiform encphalopathy. The author (M.L. Labat in 'Possible retroviral origin of prion disease: could prion disease be reconsidered as a preleukaemia syndrome?' in Biomed and Pharmacother 1999;53:47-53) suggests that the ability of a retrovirus to alter the genes of cells, their ability to introduce a leukaemia (which he claims to have found in a scrapie animal), and the finding of prion protein produced in many white blood cells all could be invovled with prion disease. For further explanation contact Colin Leakey. He feels that disarmed retrovirus carry the ability to accidentally retrotransfect genes and that this may actually be involved with the people/cattle that actually get symptoms rather than just becoming infected and remaining asymptomatic.
26. Waste water sludge involved in BSE spread. One of the researchers from Denmark noticed that the use of fertilizer made from waste water sludge was all that joined the few cases of BSE seen in Denmark. They did not even have the same supplier of meal. Kenneth Robinsson.
27. TSE associated forms of protein originate as crosslinked proteins and/or urea, formed during the chemical sterilisation steps in the processing of carcasses for re-feeding to animals. These metabolic stable compounds are absorbed and accumulated in lipophilic tissues. Professor Koss has considered how these could both be produced and could be avoided from animal artificial feed. He is welcome for comments and messages at: Prof.Koss@t-online.de
28. Phonons involved in the formation and maintainance of prions. Phonons are the smallest fragments of sound energy. They remain inside crystals and do not lose their energy resonating inside the crystals. They will donate energy to an enlarging crystal and to the change in a chemical structure that would permit the enlargement. The possibility that phonons are involved in the growth of prions in that there is a lack of information currently on how the PrPc manages to turn into the PrPsc without the energy or the solvents in the body to get this to happen. This was put forward by a physicist (Nigel Dyer) and has been fully explained. Please get in touch with S. Dealler for further discussion if you cannot contact Nigel.
29. Large increase in meat and bone meal in bovine feed in 1980s.

Because of the problems concerning the source of BSE from a single case a further hypothesis is considered as below in conjunction with Dr. A. Maddocks (0208 467 3328):
"BSE is derived from a random disease in cattle, it is not adequately destroyed by MBM rendering and it is fed to cattle. This has taken place for many years but will only be in adequate doses when UDP feeding techniques (UnDegraded Protein) are used (which were introduced progressively as of 1980). It is the offspring of these cattle that develop the symptomatic disease having become vertically infected."
This hypothesis would not require repeated peaks after an index case, it would not require the animal to have been fed any infective meal and it would not expect large numbers to become symptomatic from a single source. Also, it would expect to produce a drop in Ro early in the epidemic, without large numbers being apparently infected (although they really were). It also explains the relatively slow (after correcting for under reporting) fall in BSE cases in cattle born after the feed ban. The reason that the hypothesis was put forward was because it answered the problems listed in 'discussion' below.
The only clear problems with the hypothesis are that it cannot explain why few cases of BSE have been diagnosed in Europe* and that several cattle (about 20) would have been infected with BSE at the point at which UDP was introduced (not a single cow).
A statistical model has been made of this hypothesis but not published at this time. *NB sheep exported from the UK did develop scrapie in New Zealand and Australia and were genetically the same range as the ones that developed the disease in the UK. However the no further sheep, including the offspring of the infected sheep developed the disease. This suggests that an environmental factor is involved and the possibility must be considered that a similar factor is also involved in BSE in Europe.

30. d-amino acids alter the PrP structure. The idea is that cooked food (as MBM etc) taken in by cattle that was increased particularly at the beginning of the 1980s, that peptides heated up to high temperatures release d-aminoacids, and that these would be absorbed and would then alter the structure of PrP when they were used for its production. Intially I was sceptical but data now shows that d-aminoacids really are taken up and really are turned into human proteins. The work by Weber-J (Biochem-Piophys-Res-Commun. 1998;246:606-8) shows little d-aspartate in the PrPres but not clearly the sources of the molecule. Professor Klaus Seelig has now tested human proteins generally and found excess d-aspartate, which of course is not made in the human body.
31. The endogenous origins of spongiform encephalopathy. "Spongiform diseases occur both in animals and people. The disease is given a different name according to the species, such as CJD in humans, scrapie in sheep, BSE in cattle, and CWD (chronic wasting disease) in deer and elk. Eating meat obviously does not cause the disease in vegetarian elk or deer, therefore eating meat cannot cause it in cows, sheep, humans, or any other species. The 1981-2 newly introduced non-solvent-fat-removing-process triggered the 1986 epidemic. The previously used solvent-fat-removing-process had simultaneously dry-cleaned the fat-soluble, bio-accumulated free radicals, i.e. dioxins out of the fat. Other toxic farm practices and parasite infections probably contributed and may still be promoting the disease today. Anthony & Benjamin Parish arparish@aol.com. " They authors feel that they have specific evidence. Can I suggest looking on their web site: http://www.onshop.co.uk/bse/us_bse.htm, which seems to put over the argument well.
32. PrPsc is an intermediate form of PrPc. Infectious Prion in Transmissible Encephalopathies: The Theory with Maxwell Demon. The prion infection theory was considered from the energetics of polypeptide chain folding point of view. A discrepancy was found in the theory, related to increased enthalpy and decreased entropy of prionm olecules in the process of metamorphosis when random coiled and alpha helical spatial structure of PrPC prions change to the beta pleated sheet conformation of PrPSc. Such processes could not continue spontaneously, as they must be followed by the addition of energy and include some kind of information transfer. Such processes are thermodynamically unfavorable and a catalytic effect is here impossible. It is

full hypothesis

Antonín Galatík

Discussion:

The most likely of the above hypotheses seemed that BSE appeared spontaneously in the UK and that it was turned into an epidemic form by the transfer in MBM. However a number of problems still exist as to the epidemiology of the disease:

1. A single cow did not seem to infect many thousands but rather a small percentage of those exposed to disease. i.e. 10-100 cattle exposed for every one cow slaughered with BSE. This would expect 2-20g of bovine brain to be the infective dose. However, of cattle slaughtered late in their incubation period it would be expected that even 0.001g or less may be required to transmit the disease (complex) orally to newborn animals.
2. The index BSE case was not followed by repeated peaks but rather by a fairly linear curve.(we would have expected gradually joining peaks approximately 5 years apart: this is solved by the pituitary hypothesis as a suggestion as to how the disease spread initially). This was shown by Dealler and then published by Morris in 2000.
3. The cattle being fed the infective MBM were in fact not becoming infected when they were most exposed (i.e. when over 2 years) but rather when young or even ante natally. (Data showing it to be shortly after birth is in British Food Journal May 2001. Explanation below).
4. Some cattle that were not fed MBM when young did seem to develop BSE. This was most obvious in beef suckler herds. Although initially it seemed that sucklers were less likely to develop BSE they certainly did do so and with apparently the same incubation period as the dairy cattle. It has also been claimed that BSE has appeared in Portugal in the offspring of cattle exported from UK and in 'green' farms that did not feed any MBM to the calves.
5. The date of onset of disease has fallen marginally since the beginning of the epidemic. If cattle were fed randomly with BSE infected meal,as the epidemic progressed, the age of onset would have been expected to fall rapidly unless infection took place at a particular age and due to a particular factor.
6. The proportion of any herd that developed BSE seemed to remain low (about 15%) and the epidemic took place as a result of the increase in the herds affected rather than the increase in the number of cattle infected in specific herds. It was clear that the epidemic could not get really very high because even if all the herds in the UK were affected at a particular time, still only 15% of offspring would develop disease (if not slaughtered).
7. Herds that had already had a case of BSE were more likely to have a second than would be expected by random distribution of infected meal.
8. The Ro value (transmission rate for the disease) dropped progressively from 10 (1983) down to around 3 by 1988 (although depending on the method of calculation these figures could be much higher but in proportion). This aspect is what would be expected to have been found if certain cattle open to infection were already exposed by the time that further exposure arrived. This will not fit with the 'nugget' model of infection from MAFF.
9. The cases of BSE appeared to have been checked by the feed ban. In fact the amount of infection stopped may have been extremely large and the numbers of cases decreased by 10 fold. The most obvious factors were that the Ro was decreased to less than 1 but that animals continued to become infected and that the age distribution of disease did not change.
10. Large amounts of potentially BSE-infected feed was exported to Europe, particularly after the ban in 1988, and yet we have seen few cases of BSE diagnosed there. When calculations are carried out the numbers of cases of BSE seen in Germany and France after October 2000 suggest that there were actually quite a large number of infected animals present in the mid 1990s but we just did not identify them at the time.
11. By 2001 98% of the herds in the UK had either had a case of BSE or a case of asymptomatic BSE. Even though many herds were in different parts of the country (although southern England by far the worst affected) the disease did spread.
12. USA did exactly the same thing..(and had enough scrapie)..to its MBM. In fact it sold the UK the equipment with which to make the MBM. Yet the USA is not reporting a case of BSE.

When considering the hypotheses presented here...

Many factors may have been taking place and to assume that only one was doing so may be an error. For instance BSE may actually have been appearing in cattle in small amounts for many years...(as is claimed by some vets)...but the factor that caused the epidemic was in fact a change in its ability to transfer from one animal to the next efficiently. Changes in chemicals may have had nothing to do with the development of the disease for instance but may have permitted enough infectivity to remain in the animal feed or inocula. Changes in environmental factors may have meant that large numbers of cattle were affected by BSE at one go...and so a batch of MBM was made that had enough infectivity in it to get the infection to large numbers more. We must not forget that some TSEs do not seem to cause brain disease at all...as if they cannot transfer into the central nervous system...well could the chemicals or other infections permit this suddenly and so a disease that was present for many years could suddenly become dramatically more infectious and work as a TSE.

It is exceedingly easy to take the molecular biology that we know and assume it to be the whole of the subject. When physicists and organic chemists put their head around the door it may in fact bring much light into the field. For instance it would be easy to say that BSE started as a single animal with disease and it was fed to many more to eventually produce an epidemic. In fact the evidence for this is thin; it just makes sense to the molecular biologists and the epidemiologists. I would ask anyone reading this to beware of the tendency to make 'sensible' decisions with inadequate information and for the good of deciding the science that is required to investigate a wider range of hypotheses.

Infection taking place on farms almost entirely within the first month: faecal or meal contamination

Logic:

Rapid drop in cases of BSE born in the short period before the 1988 feed ban shows infection to be taking place within first 6 months and mostly within the first month of life. (not under argument now)
Age distribution of cattle with clinical BSE did not change as the epidemic progressed: therefore they must be getting infected with a similar dose throughout the epidemic.
Extremely low amounts likely to be found in the MBM anyway of prions.
Cattle gut mucosa will absorb large molecules easily after birth but this effect disappears within the first few months. It is thought that the effect is to permit the uptake into the bloodstream of mother's antibodies from colostrum. The mucosal resistance to this builds up and is thought to be caused by the change in diet after around 1-4 weeks of life on the farm. This would be expected to cause the dose size of BSE reaching the blood of the animal to decrease markedly as the calf gets past the first few days of life and hence the incubation period would be expected to increase. Therefore it is not surprising to find a wide range of age distribution in the cattle with clinical BSE.
Cattle developing BSE when born on farms where no MBM was used but brought from other farms and a large proportion of the calves were not fed any MBM but were suckled until relatively old (particularly in beef farms).
Cattle born within a month of each other share the chance of developing BSE to some degree. This could be at least perhaps because of feed (feed deliveries were often a month apart), shared colostrum/artificial milk, or because of contamination that was washed away at a later date.

These findings suggest that some factor is not exposed to all the cattle born at roughly the same time (e.g. common mixed colostrum) but affect a small proportion. The suggestion is that the infection is either present in environmental contamination to which the calves are exposed and is washed away, or to feed contamination that will only infect cattle if young enough to get past their gut mucosa. As a result of this a wide age distribution would be expected for clinical cases and no change in age distribution expected as a result of the feed ban. For further discussion on this contact me at deal@airtime.co.uk and I will forward your messages. One of the major investigators into this potential method of BSE transmission was Tony Austen and he should be contacted.

e-mail to

Steve Dealler at deal@airtime.co.uk

Articles for publication should be sent to me at: The Pathology Laboratory, Burnley General Hospital, Burnley, UK BB10 2PQ

It is important that we know who wants information about BSE and what you think about what is here. If you would like regular information mailed to you on the mailing list or the internet journal please tell us.

Return to the index page