10. Conclusion and Further Research Need The decrease of incidence of BSE around the world following the implementation of feed-control measures indicated that the BSE epidemic was directly caused by feeding cattle with MBM containing BSE PrPSc. The subsequent decrease in the annual number of vCJD cases is attributable to the decrease in the number of BSE cattle itself as well as the implementation of the control measures intended to exclude the BSE agent from human food. Thus, a series of the feed- and food-control measures including the measures for prevention of re-circulation of BSE PrPSc were effective at reducing the incidence of BSE and vCJD. The control measures might have lowered also the risk of human exposure to the BSE PrPSc that derived from small ruminants152,153).
In Japan, 36 cases of BSE were identified during the period from 2001 to 2007. During this period, feed-control measures including the disposal of SRM have continuously been implemented. Among the cases, two were diagnosed as L-BSE. The latest-born BSE case, which was born in January 2002, was diagnosed as C-BSE at the age of 21 months soon after the introduction of a series of the feed-control measures (the complete feed ban) in 2001. The data demonstrated that the complete feed ban was highly effective at preventing the occurrence of BSE in cattle in Japan as was the case in EU countries.
As for BARB cases, which were detected in several countries, feed-borne exposure has been regarded the most likely source of infection compared with the other possible sources.
Studies of oral administration of the C-BSE agent in cattle at their age less than 1 year shed light on the dose-dependent timing of appearance of clinical symptoms and PrPSc accumulation in the CNS. Massive doses of the brain tissue from C-BSE cases induced PrPSc accumulation in the CNS from 30 months post exposure and clinical signs from 35 months with PrPSc accumulation in the PNS. Lower doses induced PrPSc accumulation in the CNS and clinical signs at 44 months post exposure.
The brain, spinal cord, DRG, and ileum were the major locations of PrPSc accumulation in orally infected C-BSE cattle. Infectivity was higher in the ileum than in the other portions of small intestine regardless of dose. PrPSc was detected in IPP from 2 months after oral exposure, being concentrated in CPP rather than DPP. Age-dependent changes in numbers of lymph follicles and PrPSc-positive lymph follicles in the ileum imply the decrease in intestinal PrPSc with the time elapsed after oral exposure,
PrPSc was detected in the muscle in clinically affected C-BSE cattle, but not in preclinical cattle. A small amount of PrPSc deposits was also detected in muscle spindle, although its contribution to the amount of PrPSc in the whole of muscles is unclear. No infectivity was noted in fat tissues from the cattle orally inoculated with the brainstem of BSE-affected cattle.
The sporadic nature of H-BSE and L-BSE occurrence suggested that the atypical BSE may occur spontaneously rather than by feed-mediated infection. Higher zoonotic potential of L-BSE than C-BSE was suggested by some experimental studies, but the reverse was also observed by other studies. Calves were more susceptible to C-BSE than L-BSE, but the reverse was observed in non-human primates although based on a limited number of animals. Zoonotic potential of H-BSE has been suggested to be lower than that of C-BSE.
Features of tissue distribution of PrPSc in naturally or experimentally infected atypical BSE cattle resembled to those in C-BSE cattle except in the intestine, where PrPSc accumulation was not observed in the atypical BSE. PrPSc was detected in the muscle and peripheral nerves in atypical BSE cattle, but the levels were much lower than those in the CNS.
Thus, experimental and epidemiological findings accumulated during the past three decades shed light on characteristic features of BSE, and thereby led the successful reduction of BSE. However, from the perspective of food safety, unresolved issues remain even in light with the accumulated findings. The issues are as follows: a) The relative contribution of each control measure to the reduction of BSE remains mostly unclear, although the contribution was estimated for intervention strategies such as SRM removal, post-mortem testing for BSE, and culling of BSE cases in Japan136) and the Netherlands154). The estimation of relative effectiveness of other control measures is required for precise policymaking including relaxation of the regulations and rules relating to BSE in a risk-based scientifically sound manner. ; b) The ingested C-BSE PrPSc was stable in the intestinal lumen, but this remains uncertain for atypical BSE PrPSc, which was more sensitive against PK digestion than C-BSE PrPSc. ; c) Taken together with the findings in sheep, susceptibility of calves to oral C-BSE PrPSc seems likely to decrease with the increase in their age in association with the reduction of the IPP-mediated transfer of PrPSc from the intestinal lumen to the enteric nerves. However, there is no evidence which demonstrated directly the age-dependent change in bovine susceptibility to the BSE agent.; d) Most experiments of oral exposure to the BSE agent in experimental and farm animals have been performed by a single administration, but effects of repeated or long-term administration are unknown.; e) Oral infectivity of the atypical BSE agent in cattle and PrPSc accumulation in tissues of the orally infected cattle are unclear.; f) Better understanding of the risk of infection of bovine and other mammalian animals with the BSE agent via soil and grasses is required.; g) Regarding tissue distribution of PrPSc in C-BSE infected cattle, the ileal infectivity after 40 months post exposure and the quantitative significance of PrPSc deposits in muscle spindle remain uncertain.
The origin of BSE prions is also an unresolved issue. Although various hypothetical views have been presented on the origin of C-BSE142), no definitive conclusions have yet been reached. C-BSE prions might have first arisen through a PRNP gene mutation or the post-translational conversion of PrPC in individual cattle, but no evidence for either pathway exists. Among the various possible sources of C-BSE, scrapie PrPSc has been regarded as a more likely source because of the occurrence of C-BSE after changes in the rendering practices used for production of MBM, which had possibly been contaminated with scrapie PrPSc. However, the brain of sheep that were naturally infected with scrapie during the BSE epidemic in the UK caused a different disease from BSE in experimentally inoculated cattle155), suggesting that the scrapie PrPSc in its original form could not be a candidate for the origin of the BSE epidemic. However, it remains possible that the cattle affected by the epidemic were exposed to the sheep-derived PrPSc that had been modified physically in the process of rendering.
A number of studies have demonstrated that annealing, PMCA, or shaking can generate PrPSc or PrPres from purified hamster PrPC or recombinant PrP in cell-free system in the absence of PrPSc and PrPres as a “seed”156–159), indicating that the spontaneous unintended generation of PrPSc might occur in the environment under similar physical conditions. Such conditions could be found in heating, sonication, or/and shaking during the burning of cattle on farms, rendering processes, or food processing. Even if only trace amounts of PrPSc or PrPres were generated in the environment, they could act as seeds for PrPSc amplification in PrPC-rich tissues if they were ingested by animals and humans. Better understanding of the mechanism and origin of generation of BSE PrPSc may enable more precise risk assessments and pinpoint managements for prevention of food-mediated BSE-derived human diseases.
The BSE PrPSc is a unique food safety hazard due to its extremely high resistance to chemical and physical treatments despite its zoonotic potential. Accordingly, the physical and chemical treatments, such as acid- and heat-treatments that are used in food processing and cooking to prevent food-borne microbial diseases, are not effective against the BSE PrPSc. Therefore, lowering the risk of human infection with BSE via food has depended on the effort to prevent BSE infection in food-producing animals and the entry of animal tissues that might contain PrPSc into food chains.
A basic question in the management aimed at prevention of food-mediated vCJD is whether a tolerable level of intake of BSE prions exists or not. For chemical food safety hazards that are not genotoxic, no-observed-adverse-effect levels based on experimental data of feeding studies are widely used to determine tolerable levels for humans160). Dose-response relationships have been studied for BSE by experimental oral inoculation of the brain tissues containing the BSE agent to cattle and sheep24,25,161), but not in other animal species. The dose-response was studied by ic inoculation of the BSE or vCJD agent in mice57,162), but has not been studied by oral inoculation of the agent in experimental animals including mice. In addition to the lack of the data of oral dose-responses in experimental animals, the marked species difference in susceptibility that is recognized as so-called species barriers163), makes the extrapolation of animal data to humans difficult.
Furthermore, it seems difficult to find an appropriate end-point among animal responses, because dosed animals could be in subclinical stages throughout their normal life span. Studies of serial passage of the TSE agents demonstrated that TSE-inoculated animals showed no clinical symptoms and/or no detectable PrPres during their normal life span, although they harbored PrPSc89,164–166). The subclinical stage during a lifespan in experimental animals could not directly extrapolated to humans because of large differences in lifespan between animals and humans.
The analysis of data of a large number of scrapie-challenged mice suggested that no safe dose exists in terms of the threshold dose below which the probability of infection is zero167), indicating the difficulty of finding the threshold level for the BSE agent as is the case for most infectious pathogens and genotoxic carcinogens. For food safety-threatening microbial hazards, intake-disease relationships based on epidemiological data, if available, have been used in risk assessments conducted as a basis of decision of control measures168). Data available for the BSE agent are limited, but a threshold level of intake of the BSE agent in the UK population was estimated in terms of bovine infectious dose, based on the observed number of vCJD cases and the estimated quantity of the BSE agent entered to cattle-derived food169). However, the estimated value may have a limitation in its accuracy especially because of unknown variations of human individual susceptibility. Tolerable intake or intake-dependent risk in humans, if known, could be a basis for future development of cost-effective decision of the control measures aimed at reducing the risk of BSE-derived human diseases, and therefore further research into this issue is required.
PrPSc distribution of a natural case of bovine spongiform encephalopathy
Yoshifumi Iwamaru, Yuka Okubo, Tamako Ikeda, Hiroko Hayashi, Mori- kazu Imamura, Takashi Yokoyama and Morikazu Shinagawa Priori Disease Research Center, National Institute of Animal Health, 3-1-5 Kannondai, Tsukuba 305-0856 Japan gan@affrc.go.jp
Abstract
Bovine spongiform encephalopathy (BSE) is a disease of cattle that causes progressive neurodegeneration of the central nervous system. Infectivity of BSE agent is accompanied with an abnormal isoform of prion protein (PrPSc). The specified risk materials (SRM) are tissues potentially carrying BSE infectivity. The following tissues are designated as SRM in Japan: the skull including the brain and eyes but excluding the glossa and the masse- ter muscle, the vertebral column excluding the vertebrae of the tail, spinal cord, distal illeum. For a risk management step, the use of SRM in both animal feed or human food has been prohibited. However, detailed PrPSc distribution remains obscure in BSE cattle and it has caused controversies about definitions of SRM. Therefore we have examined PrPSc distribution in a BSE cattle by Western blotting to reassess definitions of SRM. The 11th BSE case in Japan was detected in fallen stock surveillance. The carcass was stocked in the refrigerator. For the detection of PrPSc, 200 mg of tissue samples were homogenized. Following collagenase treatment, samples were digested with proteinase K. After digestion, PrPSc was precipitated by sodium phosphotungstate (PTA). The pellets were subjected to Western blotting using the standard procedure. Anti-prion protein monoclonal antibody (mAb) T2 conjugated horseradish peroxidase was used for the detection of PrPSc. PrPSc was detected in brain, spinal cord, dorsal root ganglia, trigeminal ganglia, sublingual ganglion, retina. In addition, PrPSc was also detected in the peripheral nerves (sciatic nerve, tibial nerve, vagus nerve). Our results suggest that the currently accepted definitions of SRM in 9/13/2005
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Page 10 of 17
BSE cattle may need to be reexamined.
T. Kitamoto (Ed.)
PRIONS
Food and Drug Safety
================
ALSO from the International Symposium of Prion Diseases held in Sendai, October 31, to November 2, 2004; Bovine spongiform encephalopathy (BSE) in Japan
snip...
"Furthermore, current studies into transmission of cases of BSE that are atypical or that develop in young cattle are expected to amplify the BSE prion"
NO. Date conf. Farm Birth place and Date Age at diagnosis 8. 2003.10.6. Fukushima Tochigi 2001.10.13. 23 9. 2003.11.4. Hiroshima Hyogo 2002.1.13. 21 Test results # 8b, 9c cows Elisa Positive, WB Positive, IHC negative, histopathology negative b = atypical BSE case c = case of BSE in a young animal b,c, No PrPSc on IHC, and no spongiform change on histology
International Symposium of Prion Diseases held in Sendai, October 31, to November 2, 2004.
Tetsuyuki Kitamoto Professor and Chairman Department of Prion Research Tohoku University School of Medicine 2-1 SeiryoAoba-ku, Sendai 980-8575, JAPAN TEL +81-22-717-8147 FAX +81-22-717-8148 e-mail; kitamoto@mail.tains.tohoku.ac.jp Symposium Secretariat Kyomi Sasaki TEL +81-22-717-8233 FAX +81-22-717-7656 e-mail: kvomi-sasaki@mail.tains.tohoku.ac.ip
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9/13/2005
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Page 11 of 17
From: TSS
Subject: Atypical Proteinase K-Resistant Prion Protein (PrPres) observed in an Apparently Healthy 23-Month-Old Holstein Steer
Date: August 26, 2005 at 10:24 am PST
Atypical Proteinase K-Resistant Prion Protein (PrPres) observed in an Apparently Healthy 23-Month-Old Holstein Steer
Jpn. J. Infect. Dis., 56, 221-222, 2003 Laboratory and Epidemiology Communications
Atypical Proteinase K-Resistant Prion Protein (PrPres) Observed in an Apparently Healthy 23-Month-Old Holstein Steer
Yoshio Yamakawa*, KenÕichi Hagiwara, Kyoko Nohtomi, Yuko Nakamura, Masahiro Nishizima ,Yoshimi Higuchi1, Yuko Sato1, Tetsutaro Sata1 and the Expert Committee for BSE Diagnosis, Ministry of Health, Labour and Welfare of Japan2 Department of Biochemistry & Cell Biology and 1Department of Pathology, National Institute of Infectious Diseases, Tokyo 162-8640 and 2Miistry of Health, Labour and Welfare, Tokyo 100-8916
Communicated by Tetsutaro Sata (Accepted December 2, 2003) *Corresponding author: Mailing address: Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, Toyama 1-23-1, Shinjuku-ku, Tokyo 1628640, Japan. Tel: +81-3-5285-1111, Fax: +81-3-5285-1157, E-mail: yamakawa@nih.go.jp
Since October 18, 2001, 'bovine spongiform encephalopathy (BSE) examination for all cattle slaughtered at abattoirs in the country' has been mandated in Japan by the Ministry of Health, Labour and Welfare (MHLW). 'Plateria' ELISA-kit (Bio-Rad Laboratories, Hercules, Calif., USA) is routinely used at abattoirs for detecting proteinase K (PK)-resistant prion protein (PrPSc) in the obex region. Samples positive according to the ELISA screening are further subjected to Western blot (WB) and histologic and immunohistochemical examination (IHC) at the National Institute of Infectious Diseases (NIID) or Obihiro University. If PrPSc is detected either by WB or by IHC, the cattle are diagnosed as BSE. The diagnosis is approved by the Expert Committee for BSE Diagnosis, MHLW. From October 18, 2001 to September 30, 2003, approximately 2.5 million cattle were screened at abattoirs. A hundred and ten specimens positive according to ELISA were subjected to WB/IHC. Seven showed positive by both WB and IHC, all exhibiting the typical electrophoretic profile of a high content of the di-glycosylated molecular form of PrPSc (1-3) and the distinctive granular deposition of PrPSc in neuronal cells and neuropil of the dorsal nucleus of vagus. An ELISA-positive specimen from a 23 month-old Holstein steer slaughtered on September 29, 2003, in Ibaraki Prefecture (Ibaraki case) was sent to the NIID for confirmation. The animal was reportedly healthy before slaughter. The OD titer in ELISA was slightly higher than the 'cut-off' level given by the manufacturer. The histology showed no spongiform changes and IHC revealed no signal of PrPSc accumulation typical for BSE. However, WB analysis of the homogenate that was prepared from the obex region and used for ELISA revealed a small amount of PrPSc with an electrophoretic profile different from that of typical BSE-associated PrPSc (1-3). The characteristics were (i) low content of the di-glycosylated molecular form of PrPSc, (ii) a faster migration of the non-glycosylated form of PrPSc on SDS-PAGE, and (iii) less resistance against PK digestion as compared with an authentic PrPSc specimen derived from an 83-month-old Holstein (Wakayama case) (Fig. 1). Table 1 summarizes the relative amounts of three distinctive glycoforms (di-, mono, non-glycosylated) of PrPSc calculated by densitometric analysis of the blot shown in Fig. 1. As 2.5 mg wet weight obex-equivalent homogenate of the Ibaraki case (Fig. 1, lane 4) gave slightly stronger band intensities of PrPSc than an 8 mg wet weight obex-equivqlent homogenate of a typical BSE-affected Wakayama case (Fig. 1, lane 2), the amount of PrPSc accumulated in the Ibaraki case was calculated to be 1/500 - 1/1000 of the Wakayama case. In the Ibaraki case, the PrPSc bands were not detectable in the homogenates of the proximal surrounding region of the obex. These findings were consistent with the low OD value in ELISA, i.e., 0.2 -0.3 for the Ibaraki case versus over 3.0 for the Wakayama case. The DNA sequence of the PrP coding region of the Ibaraki case was the same as that appearing in the database (GenBank accession number: AJ298878). More recently, we encountered another case that resembled the Ibaraki case. It was a 21-monthold Holstein steer from Hiroshima Prefecture. WB showed typical BSE-specific PrPSc deposition though IHC did not detect positive signals of PrPSc (data not shown). Though the clinical onset of BSE is usually at around 5 years of age or later, a 20-month-old case showing the clinical signs has been reported (4). Variant forms of BSE similar to our cases, i.e., with atypical histopathological and/or biochemical phenotype, have been recently reported in Italy (5) and in France (6). Such variant BSE was not associated with mutations in the prion protein (PrP) coding region as in our case (5,6). The Ministry of Agriculture, Forestry and Fisheries of Japan (MAFF) announced a ban of feeding ruminants with meat bone meal (MBM) on September 18, 2001, and a complete ban was made on October 15 of the same year. According to the recent MAFF report, the previous seven cases of BSE in Japan were cattle born in 1995 - 1996 and possibly fed with cross-contaminated feed. However, the two cattle in this report were born after the complete ban. Whether contaminated MBM was implicated in the present cases remains to be investigated.
REFERENCES Collinge, J., Sidle, K. C. L., Meads, J., Ironside, J. and Hill, A. F. (1996): Molecular analysis of prion strain variation and the aetiology of 'new variant' CJD. Nature, 383, 685690. Bruce, M. E., Will, R. G., Ironside, J. W., McConnell, I., Drummond, D., Suttie, A., McCardle, L., Chree, A., Hope, J., Birkett, C., Cousens, S., Fraser, H. and Bostock, C. J. (1997): Transmissions to mice indicate that 'new variant' CJD is caused by the BSE agent. Nature, 389, 498-501. Hill, A. F., Desbruslais, M., Joiner, S., Sidle, K. C. L., Gowland, I. and Collinge, J. (1997): The same prion strain causes vCJD and BSE. Nature, 389, 448-450. Matravers, W., Bridgeman, J. and Smith, M.-F. (ed.)(2000): The BSE Inquiry. p. 37. vol. 16. The Stationery Office Ltd., Norwich, UK. Casalone, C., Zanusso, G., Acutis, P. L., Crescio, M. I., Corona, C., Ferrari, S., Capobianco, R., Tagliavini, F., Monaco, S. and Caramelli, M. (2003): Identification of a novel molecular and neuropathological BSE phenotype in Italy. International Conference on Prion Disease: from basic research to intervention concepts. Gasreig, Munhen, October 8-10. Bicaba, A. G., Laplanche, J. L., Ryder, S. and Baron, T. (2003): A molecular variant of bovine spongiform encephalopatie. International Conference on Prion Disease: from basic research to intervention concepts. Gasreig, Munhen, October 8-10. Asante, E. A., Linehan, J. M., Desbruslais, M., Joiner, S., Gowland, I., Wood, A. L., Welch, J., Hill, A. F., Lloyd, S. E., Wadsworth, J. D. F. and Collinge, J. (2002). BSE prions propagate as either variant CJD-like or sporadic CJD-like prion strains in transgenic mice expressing human prion protein. EMBO J., 21, 6358-6366. 9/13/2005 Page 12 of 17 SEE SLIDES IN PDF FILE; http://www.nih.go.jp/JJID/56/221.pdf
Jpn. J. Infect. Dis., 56, 221-222, 2003
Laboratory and Epidemiology Communications
Atypical Proteinase K-Resistant Prion Protein (PrPres) Observed in an Apparently Healthy 23-Month-Old Holstein Steer
Yoshio Yamakawa*, Kenﾕichi Hagiwara, Kyoko Nohtomi, Yuko Nakamura, Masahiro Nishizima ,Yoshimi Higuchi1, Yuko Sato1, Tetsutaro Sata1 and the Expert Committee for BSE Diagnosis, Ministry of Health, Labour and Welfare of Japan2
Department of Biochemistry & Cell Biology and 1Department of Pathology, National Institute of Infectious Diseases, Tokyo 162-8640 and 2Miistry of Health, Labour and Welfare, Tokyo 100-8916
Communicated by Tetsutaro Sata
(Accepted December 2, 2003)
*Corresponding author: Mailing address: Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, Toyama 1-23-1, Shinjuku-ku, Tokyo 162-8640, Japan. Tel: +81-3-5285-1111, Fax: +81-3-5285-1157, E-mail: yamakawa@nih.go.jp
Since October 18, 2001, 'bovine spongiform encephalopathy (BSE) examination for all cattle slaughtered at abattoirs in the country' has been mandated in Japan by the Ministry of Health, Labour and Welfare (MHLW). 'Plateria' ELISA-kit (Bio-Rad Laboratories, Hercules, Calif., USA) is routinely used at abattoirs for detecting proteinase K (PK)-resistant prion protein (PrPSc) in the obex region. Samples positive according to the ELISA screening are further subjected to Western blot (WB) and histologic and immunohistochemical examination (IHC) at the National Institute of Infectious Diseases (NIID) or Obihiro University. If PrPSc is detected either by WB or by IHC, the cattle are diagnosed as BSE. The diagnosis is approved by the Expert Committee for BSE Diagnosis, MHLW. From October 18, 2001 to September 30, 2003, approximately 2.5 million cattle were screened at abattoirs. A hundred and ten specimens positive according to ELISA were subjected to WB/IHC. Seven showed positive by both WB and IHC, all exhibiting the typical electrophoretic profile of a high content of the di-glycosylated molecular form of PrPSc (1-3) and the distinctive granular deposition of PrPSc in neuronal cells and neuropil of the dorsal nucleus of vagus.
An ELISA-positive specimen from a 23 month-old Holstein steer slaughtered on September 29, 2003, in Ibaraki Prefecture (Ibaraki case) was sent to the NIID for confirmation. The animal was reportedly healthy before slaughter. The OD titer in ELISA was slightly higher than the 'cut-off' level given by the manufacturer. The histology showed no spongiform changes and IHC revealed no signal of PrPSc accumulation typical for BSE. However, WB analysis of the homogenate that was prepared from the obex region and used for ELISA revealed a small amount of PrPSc with an electrophoretic profile different from that of typical BSE-associated PrPSc (1-3). The characteristics were (i) low content of the di-glycosylated molecular form of PrPSc, (ii) a faster migration of the non-glycosylated form of PrPSc on SDS-PAGE, and (iii) less resistance against PK digestion as compared with an authentic PrPSc specimen derived from an 83-month-old Holstein (Wakayama case) (Fig. 1). Table 1 summarizes the relative amounts of three distinctive glycoforms (di-, mono, non-glycosylated) of PrPSc calculated by densitometric analysis of the blot shown in Fig. 1. As 2.5 mg wet weight obex-equivalent homogenate of the Ibaraki case (Fig. 1, lane 4) gave slightly stronger band intensities of PrPSc than an 8 mg wet weight obex-equivqlent homogenate of a typical BSE-affected Wakayama case (Fig. 1, lane 2), the amount of PrPSc accumulated in the Ibaraki case was calculated to be 1/500 - 1/1000 of the Wakayama case. In the Ibaraki case, the PrPSc bands were not detectable in the homogenates of the proximal surrounding region of the obex. These findings were consistent with the low OD value in ELISA, i.e., 0.2 - 0.3 for the Ibaraki case versus over 3.0 for the Wakayama case. The DNA sequence of the PrP coding region of the Ibaraki case was the same as that appearing in the database (GenBank accession number: AJ298878). More recently, we encountered another case that resembled the Ibaraki case. It was a 21-month-old Holstein steer from Hiroshima Prefecture. WB showed typical BSE-specific PrPSc deposition though IHC did not detect positive signals of PrPSc (data not shown).
Though the clinical onset of BSE is usually at around 5 years of age or later, a 20-month-old case showing the clinical signs has been reported (4). Variant forms of BSE similar to our cases, i.e., with atypical histopathological and/or biochemical phenotype, have been recently reported in Italy (5) and in France (6). Such variant BSE was not associated with mutations in the prion protein (PrP) coding region as in our case (5,6).
The Ministry of Agriculture, Forestry and Fisheries of Japan (MAFF) announced a ban of feeding ruminants with meat bone meal (MBM) on September 18, 2001, and a complete ban was made on October 15 of the same year. According to the recent MAFF report, the previous seven cases of BSE in Japan were cattle born in 1995 - 1996 and possibly fed with cross-contaminated feed. However, the two cattle in this report were born after the complete ban. Whether contaminated MBM was implicated in the present cases remains to be investigated.
REFERENCES
Collinge, J., Sidle, K. C. L., Meads, J., Ironside, J. and Hill, A. F. (1996): Molecular analysis of prion strain variation and the aetiology of 'new variant' CJD. Nature, 383, 685-690. Bruce, M. E., Will, R. G., Ironside, J. W., McConnell, I., Drummond, D., Suttie, A., McCardle, L., Chree, A., Hope, J., Birkett, C., Cousens, S., Fraser, H. and Bostock, C. J. (1997): Transmissions to mice indicate that 'new variant' CJD is caused by the BSE agent. Nature, 389, 498-501. Hill, A. F., Desbruslais, M., Joiner, S., Sidle, K. C. L., Gowland, I. and Collinge, J. (1997): The same prion strain causes vCJD and BSE. Nature, 389, 448-450. Matravers, W., Bridgeman, J. and Smith, M.-F. (ed.)(2000): The BSE Inquiry. p. 37. vol. 16. The Stationery Office Ltd., Norwich, UK. Casalone, C., Zanusso, G., Acutis, P. L., Crescio, M. I., Corona, C., Ferrari, S., Capobianco, R., Tagliavini, F., Monaco, S. and Caramelli, M. (2003): Identification of a novel molecular and neuropathological BSE phenotype in Italy. International Conference on Prion Disease: from basic research to intervention concepts. Gasreig, Munhen, October 8-10. Bicaba, A. G., Laplanche, J. L., Ryder, S. and Baron, T. (2003): A molecular variant of bovine spongiform encephalopatie. International Conference on Prion Disease: from basic research to intervention concepts. Gasreig, Munhen, October 8-10. Asante, E. A., Linehan, J. M., Desbruslais, M., Joiner, S., Gowland, I., Wood, A. L., Welch, J., Hill, A. F., Lloyd, S. E., Wadsworth, J. D. F. and Collinge, J. (2002). BSE prions propagate as either variant CJD-like or sporadic CJD-like prion strains in transgenic mice expressing human prion protein. EMBO J., 21, 6358-6366.
MONDAY, JUNE 19, 2017
PRION 2017 P20 Descriptive epidemiology of human prion diseases in Japan: a prospective 16-year surveillance study
Japan Prion Disease Increasing Annually to 2.3 patients per 1 million populations in 2014
P.108: Successful oral challenge of adult cattle with classical BSE
Sandor Dudas1,*, Kristina Santiago-Mateo1, Tammy Pickles1, Catherine Graham2, and Stefanie Czub1 1Canadian Food Inspection Agency; NCAD Lethbridge; Lethbridge, Alberta, Canada; 2Nova Scotia Department of Agriculture; Pathology Laboratory; Truro, Nova Scotia, Canada
Classical Bovine spongiform encephalopathy (C-type BSE) is a feed- and food-borne fatal neurological disease which can be orally transmitted to cattle and humans. Due to the presence of contaminated milk replacer, it is generally assumed that cattle become infected early in life as calves and then succumb to disease as adults. Here we challenged three 14 months old cattle per-orally with 100 grams of C-type BSE brain to investigate age-related susceptibility or resistance. During incubation, the animals were sampled monthly for blood and feces and subjected to standardized testing to identify changes related to neurological disease. At 53 months post exposure, progressive signs of central nervous system disease were observed in these 3 animals, and they were euthanized. Two of the C-BSE animals tested strongly positive using standard BSE rapid tests, however in 1 C-type challenged animal, Prion 2015 Poster Abstracts S67 PrPsc was not detected using rapid tests for BSE. Subsequent testing resulted in the detection of pathologic lesion in unusual brain location and PrPsc detection by PMCA only.
***Our study demonstrates susceptibility of adult cattle to oral transmission of classical BSE.
We are further examining explanations for the unusual disease presentation in the third challenged animal.
SATURDAY, JANUARY 5, 2019
Low levels of classical BSE infectivity in rendered fat tissue
***> This study demonstrates that the H-type BSE agent is transmissible by the oronasal route.
***> These results reinforce the need for ongoing surveillance for classical and atypical BSE to minimize the risk of potentially infectious tissues entering the animal or human food chains.
even the atypical h-type BSE was found to be transmissible by oral route, and those findings can be found at the Prion 2018 Conference abstract.
PRION 2018 CONFERENCE
P98 The agent of H-type bovine spongiform encephalopathy associated with E211K prion protein polymorphism transmits after oronasal challenge
Greenlee JJ (1), Moore SJ (1), and West Greenlee MH (2)
(1) United States Department of Agriculture, Agricultural Research Service, National Animal Disease Center, Virus and Prion Research Unit, Ames, IA, United States (2) Department of Biomedical Sciences, Iowa State University College of Veterinary Medicine, Ames, IA, United States.
In 2006, a case of H-type bovine spongiform encephalopathy (BSE) was reported in a cow with a previously unreported prion protein polymorphism (E211K).
The E211K polymorphism is heritable and homologous to the E200K mutation in humans that is the most frequent PRNP mutation associated with familial Creutzfeldt-Jakob disease.
Although the prevalence of the E211K polymorphism is low, cattle carrying the K211 allele develop H-type BSE with a rapid onset after experimental inoculation by the intracranial route.
The purpose of this study was to investigate whether the agents of H-type BSE or H-type BSE associated with the E211K polymorphism transmit to wild type cattle or cattle with the K211 allele after oronasal exposure.
Wild type (EE211) or heterozygous (EK211) cattle were oronasally inoculated with either H-type BSE from the 2004 US Htype BSE case (n=3) or from the 2006 US H-type case associated with the E211K polymorphism (n=4) using 10% w/v brain homogenates.
Cattle were observed daily throughout the course of the experiment for the development of clinical signs.
At approximately 50 months post-inoculation, one steer (EK211 inoculated with E211K associated H-BSE) developed clinical signs including inattentiveness, loss of body condition, weakness, ataxia, and muscle fasciculations and was euthanized.
Enzyme immunoassay confirmed that abundant misfolded protein was present in the brainstem, and immunohistochemistry demonstrated PrPSc throughout the brain.
Western blot analysis of brain tissue from the clinically affected steer was consistent with the E211K H-type BSE inoculum.
With the experiment currently at 55 months post-inoculation, no other cattle in this study have developed clinical signs suggestive of prion disease.
***> This study demonstrates that the H-type BSE agent is transmissible by the oronasal route.
***> These results reinforce the need for ongoing surveillance for classical and atypical BSE to minimize the risk of potentially infectious tissues entering the animal or human food chains.
PRION 2018 CONFERENCE
P98 The agent of H-type bovine spongiform encephalopathy associated with E211K prion protein polymorphism transmits after oronasal challenge
Greenlee JJ (1), Moore SJ (1), and West Greenlee MH (2) (1) United States Department of Agriculture, Agricultural Research Service, National Animal Disease Center, Virus and Prion Research Unit, Ames, IA, United States (2) Department of Biomedical Sciences, Iowa State University College of Veterinary Medicine, Ames, IA, United States.
reading up on this study from Prion 2018 Conference, very important findings ;
***> This study demonstrates that the H-type BSE agent is transmissible by the oronasal route.
***> These results reinforce the need for ongoing surveillance for classical and atypical BSE to minimize the risk of potentially infectious tissues entering the animal or human food chains.
PRION 2018 CONFERENCE ABSTRACT
***> This study demonstrates that the H-type BSE agent is transmissible by the oronasal route.
***> These results reinforce the need for ongoing surveillance for classical and atypical BSE to minimize the risk of potentially infectious tissues entering the animal or human food chains.
WEDNESDAY, OCTOBER 24, 2018
Experimental Infection of Cattle With a Novel Prion Derived From Atypical H-Type Bovine Spongiform Encephalopathy
WEDNESDAY, MARCH 15, 2017
In vitro amplification of H-type atypical bovine spongiform encephalopathy by protein misfolding cyclic amplification
"When considering the atypical L-BSE and H-BSE diseases of cattle, they have been assessed in both non-human primate and transgenic mouse bioassays (with mice transgenic for human PRNP) and both model systems indicate that H-BSE and L-BSE may have increased zoonotic potential compare with C-BSE.
***The detection of all types of BSE is therefore of significant importance."
Experimental Transmission of H-type Bovine Spongiform Encephalopathy to Bovinized Transgenic Mice
Vet Pathol 0300985810382672, first published on October 4, 2010
Experimental Transmission of H-type Bovine Spongiform Encephalopathy to Bovinized Transgenic Mice
H. Okada okadahi@affrc.go.jp Prion Disease Research Center, National Institute of Animal Health, Tsukuba, K. Masujin Prion Disease Research Center, National Institute of Animal Health, Tsukuba, Y. Imamaru Prion Disease Research Center, National Institute of Animal Health, Tsukuba, M. Imamura Prion Disease Research Center, National Institute of Animal Health, Tsukuba, Y. Matsuura Prion Disease Research Center, National Institute of Animal Health, Tsukuba, S. Mohri Prion Disease Research Center, National Institute of Animal Health, Tsukuba, S. Czub Animal Disease Research Institute, Canadian Food Inspection Agency, T. Yokoyama Prion Disease Research Center, National Institute of Animal Health, Tsukuba,
Abstract
To characterize the biological and biochemical properties of H-type bovine spongiform encephalopathy (BSE), a transmission study with a Canadian H-type isolate was performed with bovinized transgenic mice (TgBoPrP), which were inoculated intracerebrally with brain homogenate from cattle with H-type BSE. All mice exhibited characteristic neurologic signs, and the subsequent passage showed a shortened incubation period. The distribution of disease-associated prion protein (PrPSc) was determined by immunohistochemistry, Western blot, and paraffin-embedded tissue (PET) blot. Biochemical properties and higher molecular weight of the glycoform pattern were well conserved within mice. Immunolabeled granular PrPSc, aggregates, and/or plaque-like deposits were mainly detected in the following brain locations: septal nuclei, subcallosal regions, hypothalamus, paraventricular nucleus of the thalamus, interstitial nucleus of the stria terminalis, and the reticular formation of the midbrain. Weak reactivity was detected by immunohistochemistry and PET blot in the cerebral cortex, most thalamic nuclei, the hippocampus, medulla oblongata, and cerebellum. These findings indicate that the H-type BSE prion has biological and biochemical properties distinct from those of C-type and L-type BSE in TgBoPrP mice, which suggests that TgBoPrP mice constitute a useful animal model to distinguish isolates from BSE-infected cattle.
© 2010 Sage Publications, Inc.
Thursday, October 07, 2010
Experimental Transmission of H-type Bovine Spongiform Encephalopathy to Bovinized Transgenic Mice
MONDAY, JANUARY 09, 2017
Oral Transmission of L-Type Bovine Spongiform Encephalopathy Agent among Cattle
CDC Volume 23, Number 2—February 2017
*** Consumption of L-BSE–contaminated feed may pose a risk for oral transmission of the disease agent to cattle.
*** Consumption of L-BSE–contaminated feed may pose a risk for oral transmission of the disease agent to cattle.
PPo2-26:
Transmission of Classical and Atypical (L-type) Bovine Spongiform Encephalopathy (BSE) Prions to Cynomolgus macaques
Fumiko Ono,1 Yoshio Yamakawa,2 Minoru Tobiume,3 Yuko Sato,3 Harutaka Katano,3 Kenichi Hagiwara,2 Iori Itagaki,1 Akio Hiyaoka,1 Katuhiko Komatuzaki,1 Yasunori Emoto,1 Hiroaki Shibata,4 Yuichi Murayama,5 Keiji Terao,4 Yasuhiro Yasutomi4 and Tetsutaro Sata3
1The Corporation for Production and Research of Laboratory Primates; Tsukuba City, Japan; 2Departments of Cell Biology and Biochemistry; and 3Pathology; National Institute of Infectious Diseases; Tokyo, Japan; 4Tsukuba Primate Research Center; National Institute of Biomedical Innovation; Tsukuba City, Japan; 5Prion Disease Research Team; National Institute of Animal Health; Tsukuba City, Japan
Key words: L-type BSE, cBSE, cynomolgus macaques, transmission
BSE prion derived from classical BSE (cBSE) or L-type BSE was characterized by inoculation into the brain of cynomolgus macaques. The neurologic manifestation was developed in all cynomolgus macaques at 27-43 months after intracerebral inoculation of brain homogenate from cBSE-affected cattle (BSE JP/6). Second transmission of cBSE from macaque to macaque shortened incubation period to 13-18 months. cBSE-affected macaques showed the similar clinical signs including hyperekplexia, tremor and paralysis in both primary and second transmission.
Two macaques were intracerebrally inoculated brain homogenate from the L-type BSE-affected cattle (BSE JP/24). The incubation periods were 19-20 months in primary transmission.
The clinical course of the L-type BSE-affected macaques differed from that in cBSE-affected macaques in the points of severe myoclonus without hyperekplexia. The glycoform profile of PrPSc detected in macaque CNS was consistent with original pattern of either cBSE or L-typeBSE PrPSc, respectively. Although severe spongiform change in the brain was remarkable in all BSE-affected macaques, severe spongiform spread widely in cerebral cortex in L-type BSE-affected macaques. Heavy accumulation of PrPSc surrounded by vacuola formed florid plaques in cerebral cortex of cBSE-affected macaques. Deposit of PrPSc in L-type BSE-affected macaque was weak and diffuse synaptic pattern in cerebrum, but large PrPSc plaques were evident at cerebellum. MRI analysis, T2, T1, DW and flair sequences, at the time of autopsy revealed that brain atrophy and dilatation of cerebral ventricles were significantly severe in L-type BSE-affected macaques. These results suggest that L-type BSE is more virulent strain to primates comparing to cBSE.
Saturday, June 25, 2011
Transmissibility of BSE-L and Cattle-Adapted TME Prion Strain to Cynomolgus Macaque
"BSE-L in North America may have existed for decades"
Tuesday, September 10, 2019
FSIS [Docket No. FSIS–2019–0021] Notice of Request To Renew an Approved Information Collection: Specified Risk Materials Singeltary Submission
Wednesday, January 23, 2019
CFIA SFCR Guidance on Specified risk material (SRM) came into force on January 15, 2019
TUESDAY, AUGUST 28, 2018
USDA finds BSE infection in Florida cow 08/28/18 6:43 PM
WEDNESDAY, AUGUST 29, 2018
USDA Announces Atypical Bovine Spongiform Encephalopathy Detection USDA 08/29/2018 10:00 AM EDT
WEDNESDAY, AUGUST 29, 2018
Transmissible Spongiform Encephalopathy TSE Prion Atypical BSE Confirmed Florida Update USA August 28, 2018
THURSDAY, JULY 20, 2017
USDA OIE Alabama Atypical L-type BASE Bovine Spongiform Encephalopathy BSE animal feeds for ruminants rule, 21 CFR 589.200
cattle, pigs, sheep, cwd, tse, prion, oh my!
***> In contrast, cattle are highly susceptible to white-tailed deer CWD and mule deer CWD in experimental conditions but no natural CWD infections in cattle have been reported (Sigurdson, 2008; Hamir et al., 2006).
Sheep and cattle may be exposed to CWD via common grazing areas with affected deer but so far, appear to be poorly susceptible to mule deer CWD (Sigurdson, 2008). In contrast, cattle are highly susceptible to white-tailed deer CWD and mule deer CWD in experimental conditions but no natural CWD infections in cattle have been reported (Sigurdson, 2008; Hamir et al., 2006). It is not known how susceptible humans are to CWD but given that the prion can be present in muscle, it is likely that humans have been exposed to the agent via consumption of venison (Sigurdson, 2008). Initial experimental research suggests that human susceptibility to CWD is low and there may be a robust species barrier for CWD transmission to humans (Sigurdson, 2008), however the risk appetite for a public health threat may still find this level unacceptable.
2020
cwd scrapie pigs oral routes
***> However, at 51 months of incubation or greater, 5 animals were positive by one or more diagnostic methods. Furthermore, positive bioassay results were obtained from all inoculated groups (oral and intracranial; market weight and end of study) suggesting that swine are potential hosts for the agent of scrapie. <***
>*** Although the current U.S. feed ban is based on keeping tissues from TSE infected cattle from contaminating animal feed, swine rations in the U.S. could contain animal derived components including materials from scrapie infected sheep and goats. These results indicating the susceptibility of pigs to sheep scrapie, coupled with the limitations of the current feed ban, indicates that a revision of the feed ban may be necessary to protect swine production and potentially human health. <***
***> Results: PrPSc was not detected by EIA and IHC in any RPLNs. All tonsils and MLNs were negative by IHC, though the MLN from one pig in the oral <6 5="" 6="" at="" by="" detected="" eia.="" examined="" group="" in="" intracranial="" least="" lymphoid="" month="" months="" of="" one="" pigs="" positive="" prpsc="" quic="" the="" tissues="" was="">6 months group, 5/6 pigs in the oral <6 4="" and="" group="" months="" oral="">6 months group. Overall, the MLN was positive in 14/19 (74%) of samples examined, the RPLN in 8/18 (44%), and the tonsil in 10/25 (40%).
***> Conclusions: This study demonstrates that PrPSc accumulates in lymphoid tissues from pigs challenged intracranially or orally with the CWD agent, and can be detected as early as 4 months after challenge. CWD-infected pigs rarely develop clinical disease and if they do, they do so after a long incubation period.
This raises the possibility that CWD-infected pigs could shed prions into their environment long before they develop clinical disease.
Furthermore, lymphoid tissues from CWD-infected pigs could present a potential source of CWD infectivity in the animal and human food chains.
Friday, December 14, 2012
DEFRA U.K. What is the risk of Chronic Wasting Disease CWD being introduced into Great Britain? A Qualitative Risk Assessment October 2012
snip.....
In the USA, under the Food and Drug Administration's BSE Feed Regulation (21 CFR 589.2000) most material (exceptions include milk, tallow, and gelatin) from deer and elk is prohibited for use in feed for ruminant animals. With regards to feed for non-ruminant animals, under FDA law, CWD positive deer may not be used for any animal feed or feed ingredients. For elk and deer considered at high risk for CWD, the FDA recommends that these animals do not enter the animal feed system. However, this recommendation is guidance and not a requirement by law.
Animals considered at high risk for CWD include:
1) animals from areas declared to be endemic for CWD and/or to be CWD eradication zones and
2) deer and elk that at some time during the 60-month period prior to slaughter were in a captive herd that contained a CWD-positive animal.
Therefore, in the USA, materials from cervids other than CWD positive animals may be used in animal feed and feed ingredients for non-ruminants.
The amount of animal PAP that is of deer and/or elk origin imported from the USA to GB can not be determined, however, as it is not specified in TRACES. It may constitute a small percentage of the 8412 kilos of non-fish origin processed animal proteins that were imported from US into GB in 2011.
Overall, therefore, it is considered there is a __greater than negligible risk___ that (nonruminant) animal feed and pet food containing deer and/or elk protein is imported into GB.
There is uncertainty associated with this estimate given the lack of data on the amount of deer and/or elk protein possibly being imported in these products.
snip.....
36% in 2007 (Almberg et al., 2011). In such areas, population declines of deer of up to 30 to 50% have been observed (Almberg et al., 2011). In areas of Colorado, the prevalence can be as high as 30% (EFSA, 2011).
The clinical signs of CWD in affected adults are weight loss and behavioural changes that can span weeks or months (Williams, 2005). In addition, signs might include excessive salivation, behavioural alterations including a fixed stare and changes in interaction with other animals in the herd, and an altered stance (Williams, 2005). These signs are indistinguishable from cervids experimentally infected with bovine spongiform encephalopathy (BSE).
Given this, if CWD was to be introduced into countries with BSE such as GB, for example, infected deer populations would need to be tested to differentiate if they were infected with CWD or BSE to minimise the risk of BSE entering the human food-chain via affected venison.
snip.....
The rate of transmission of CWD has been reported to be as high as 30% and can approach 100% among captive animals in endemic areas (Safar et al., 2008).
snip.....
In summary, in endemic areas, there is a medium probability that the soil and surrounding environment is contaminated with CWD prions and in a bioavailable form. In rural areas where CWD has not been reported and deer are present, there is a greater than negligible risk the soil is contaminated with CWD prion.
snip.....
In summary, given the volume of tourists, hunters and servicemen moving between GB and North America, the probability of at least one person travelling to/from a CWD affected area and, in doing so, contaminating their clothing, footwear and/or equipment prior to arriving in GB is greater than negligible... For deer hunters, specifically, the risk is likely to be greater given the increased contact with deer and their environment. However, there is significant uncertainty associated with these estimates.
snip.....
Therefore, it is considered that farmed and park deer may have a higher probability of exposure to CWD transferred to the environment than wild deer given the restricted habitat range and higher frequency of contact with tourists and returning GB residents.
snip.....
TUESDAY, APRIL 18, 2017
*** EXTREME USA FDA PART 589 TSE PRION FEED LOOP HOLE STILL EXIST, AND PRICE OF POKER GOES UP ***
WEDNESDAY, JULY 11, 2018
CONFIDENTIAL IN CONFIDENCE SPONGIFORM ENCEPHALOPATHY OF PIGS FDA EMERGENCY REQUEST FOR RULE CHANGE USA Section 21 C.F.R. 589.2000
TUESDAY, JULY 10, 2018
CONFIDENTIAL IN CONFIDENCE SPONGIFORM ENCEPHALOPATHY OF PIGS
*** ''but feeding of other ruminant protein, including scrapie-infected sheep, can continue to pigs.''
CONFIDENTIAL SPONGIFORM ENCEPHALOPATHY OF PIGS
***> NEW TRANSMISSIBLE SPONGIFORM ENCEPHALOPATHY TSE PRION DISEASE (MAD CAMEL DISEASE) IN A NEW SPECIES <***
NEW OUTBREAK OF TRANSMISSIBLE SPONGIFORM ENCEPHALOPATHY TSE PRION DISEASE IN A NEW SPECIES
Subject: Prion Disease in Dromedary Camels, Algeria
Our identification of this prion disease in a geographically widespread livestock species requires urgent enforcement of surveillance and assessment of the potential risks to human and animal health.
Wednesday, May 30, 2018
Dromedary camels in northern Africa have a neurodegenerative prion disease that may have originated decades ago
***> IMPORTS AND EXPORTS <***
SEE MASSIVE AMOUNTS OF BANNED ANIMAL PROTEIN AKA MAD COW FEED IN COMMERCE USA DECADES AFTER POST BAN
Thursday, August 1, 2019
Camel prion disease detected in Tunisian camels
THURSDAY, AUGUST 08, 2019
Raccoons accumulate PrPSc after intracranial inoculation with the agents of chronic wasting disease (CWD) or transmissible mink encephalopathy (TME) but not atypical scrapie
FRIDAY, JULY 26, 2019
Chronic Wasting Disease in Cervids: Implications for Prion Transmission to Humans and Other Animal Species
MONDAY, FEBRUARY 25, 2019
MAD DOGS AND ENGLISHMEN BSE, SCRAPIE, CWD, CJD, TSE PRION A REVIEW 2019
THE USA FDA MAD COW FEED BAN OF 1997 WAS NOTHING MORE THAN INK ON PAPER, NEVER ENFORCED...terry
SUNDAY, SEPTEMBER 1, 2019
FDA Reports on VFD Compliance
Before and after the current Veterinary Feed Directive (VFD) rules took full effect in January, 2017, the FDA focused primarily on education and outreach to help feed mills, veterinarians and producers understand and comply with the requirements. Since then, FDA has gradually increased the number of VFD inspections and initiated enforcement actions when necessary.
SATURDAY, DECEMBER 21, 2019
In vitro detection of haematogenous prions in white-tailed deer orally dosed with low concentrations of chronic wasting disease
