ATYPICAL BSE IN AUSTRIA
More than 10 years of extensive BSE screening in Austria resulted in a total of 8 positive cases of BSE up till August 2011. Five of these cases were classified as C-type BSE, one of them behaving peculiar. The three latest cases are of atypical BSE, being 2 L-type cases and 1 H-type case.
This fact rises the question if we now have reached the end of the C-type BSE epidemic and dip into a basic noise of spontaneously appearing prion diseases.
Common bovine spongiform encephalopathy (C-type BSE) has been accounted for spread of the BSE-epidemic from UK to other countries. Rare aberrant BSE types H and L have been found in animals aging 8 years and more. In Austria only 8 cases of BSE have been detected, coded AU1 – AU8. Two were from 6 year old animals, the others were derived from animals above the age of 10. The potential presence of aberrant types was investigated.
The first five cases behaved as C-type, while two later cases had typical properties of L-type BSE or BASE (AU6 and AU7, Fig. 1) and the latest case turned out to be an H-type case (AU8) as quantified for PrPres aspects such as N terminus, glycoprofile, proteinase K resistance (Fig 2), and dual glycotype (Fig. 3). One of the C-type cases (AU5, age 12.5 yr) behaved peculiar, because its binding to antibodies 12B2 and P4 was unusually strong and equal compared to that of core antibody L42.
The fact that BSE types L and H are found in low BSE-incidence countries like Sweden, Denmark, USA, Japan, Canada, and now also 2 L-types and 1 H-type in Austria is indicative for natural presence of sporadic BSE in different forms. Case AU5 is peculiar (C-typeP4/12B2); no more tissue is available for further studies. Monitoring the food chain for BSE on the long term is sensible when the old age animals (> 7 years) remain the target. It might show indirectly the probable source of the BSE epidemic.
MATERIAL AND METHODS
All cases have been detected during the active screening program using all kinds of Prionics BSE rapid tests. One Austrian case was found at a German laboratory using Bio-Rad TeEsE. Confirmatory testing at the Austrian NRL for TSE at AGES IVET Mödling was done by using classical OIE Western blot or immunohistochemistry or Bio-Rad TeSeE Western blot assay (Bio- Rad Laboratories).
Similar methods on brain stem homogenates as published before (Jacobs et al., 2007) were used; PrPres analysis was performed on western blots using group A, B and C antibodies, including testing of the protease susceptibility.
H. Schildorfer1, Jo H.F. Erkens2, Jorg G. Jacobs2, Alex Bossers2, Ines Rammel1, F. Schmoll1, Jan P.M. Langeveld2 1Austrian Agency for Health and Food Safety, Institute for Veterinary Disease Control, Mödling, Austria 2Central Veterinary Institute of Wageningen UR, PO Box 65, 8200 AB Lelystad, The Netherlands
Figure 1: Differentiation between C-type cases and atypical types H- and L-type cases by analysing the PrPres protease resistance using two different PK digestion conditions. Above the lanes the two different pH conditions are indicated: suboptimal condition at pH6.5 (50 >g PK/mL) and optimal condition at pH8 (500 >g PK/mL). Tissue equivalents applied per lane were for Scr, AU3 and AU3 (0.06 mg), AU5, AU6, L, H (0.25 mg), AU7 and AU8 (0.125 mg).
Jacobs, JG, Langeveld JPM, Biacabe A-G, Acutis P-L, Polak M P, Gavier-Widen D, Buschmann A, Caramelli M, Casalone C, Mazza M, Groschup M, Erkens JHF, Davidse A, van Zijderveld FG, Baron 2007. Molecular discrimination of atypical bovine spongiform encephalopathy strains from a geographical region spanning a wide area in Europe. J Clin Microbiol.45:1821-1829.
- Creutzfeldt-Jakob disease
- Transmissible spongiform encephalopathy
- Prion protein
- 14-3-3 protein
Background: Definite diagnosis of prion diseases or transmissible spongiform encephalopathies (TSEs) requires neuropathology, usually at autopsy. Epidemiology of human TSEs has relied on definite as well as ‘probable’ cases in which neuropathological confirmation is lacking, usually because of low autopsy rates in most countries. Methods: In Austria, an active surveillance program for human prion diseases was established in 1996. Since then, more than 900 referrals were analyzed. Postmortem investigation of brain tissue is mandatory in every suspect case of TSE. Thus, epidemiological data on TSEs from Austria may serve as autopsy-controlled reference for countries with lower autopsy rates. Results: The total number of TSE cases in Austria since 1969 is 206. The average yearly mortality for the active surveillance period from 1996 to 30 June 2006 is 1.39 per million, with the highest rates for Vienna (2.37) compared with other provinces. Eighty-five percent of definite TSEs were classified as sporadic Creutzfeldt-Jakob disease (sCJD). We observed a significant linear increase in the mean age at death of 0.6 years per calendar year. Clinical diagnostic surveillance criteria had a sensitivity and specificity of 82.7 and 80.0% for probable CJD, respectively, and a positive predictive value of 80.5% for probable and 38.9% for ‘possible’ CJD. Alternative neuropathological diagnoses in suspect cases included Alzheimer’s disease with or without Lewy body pathology, vascular encephalopathy, metabolic encephalopathies and viral or limbic encephalitis. Conclusion: The steady increase in mortality rates, especially in old age groups, most likely reflects improved case ascertainment due to active surveillance causing higher awareness of the medical community. In comparison with other European countries, it is reassuring to note that the overall death rate of TSEs does not differ from the Austrian autopsy-controlled data, thus confirming the value of clinical surveillance criteria.
Copyright © 2008 S. Karger AG, Basel
***Oral Transmission of L-type Bovine Spongiform Encephalopathy in Primate Model
***Infectivity in skeletal muscle of BASE-infected cattle
***feedstuffs- It also suggests a similar cause or source for atypical BSE in these countries.
***Also, a link is suspected between atypical BSE and some apparently sporadic cases of Creutzfeldt-Jakob disease in humans.
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