Epidemiological and genetical differences between classical and atypical scrapie cases

Department of Animal Breeding and Genetics, Justus-Liebig University of Giessen, 35390 Giessen, Germany.
Veterinary Research (Impact Factor: 2.82). 01/2007; 38(1):65-80. DOI: 10.1051/vetres:2006046
Source: PubMed


The aim of this study was to analyze the epidemiology and prion protein (PrP) genetics in scrapie-affected sheep flocks in Germany. For this purpose, 224 German scrapie cases in sheep diagnosed between January 2002 and February 2006 were classified as classical or atypical scrapie and the amino acids at codons 136, 141, 154 and 171 were determined. Likewise, representative numbers of flock mates were genotyped. Significant epidemiological differences were observed between classical and atypical scrapie cases in regard to the numbers of scrapie-affected sheep within a flock, the sizes of flocks with only a single scrapie-positive sheep or more than one scrapie-positive sheep and the age distribution of the scrapie-positive sheep. Sheep with the ARQ/ARQ genotype had by far the highest risk for acquiring classical scrapie, but the risk for atypical scrapie was the highest for sheep carrying phenylalanine (F) at position 141 (AF(141)RQ) and/or the AHQ haplotype. However, atypical scrapie also occurred with a notable frequency in sheep with the PrP haplotypes ARR and/or ARQ in combination with Leucine at position 141 (AL(141)RQ). Furthermore, six atypical scrapie-positive sheep carried the PrP genotype ARR/ARR. The high proportion of sheep flocks affected by atypical scrapie underscores the importance of this scrapie type.

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Available from: Horst Brandt, Jun 04, 2014
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    • "In all the scrapie cases we examined, the animals were LL homozygous in codon 141. These data are in accordance with the results of Moum et al. [25] and Lühken et al. [23], who also report the resistance allele ARR in the classical type of scrapie and the AHQ allele associated with lower susceptibility in sheep affected by atypical scrapie. The high-susceptibility VRQ allele was found in all the flocks studied by us, except flock number 2. The AHQ allele, which is associated with high resistance and a longer incubation period [26] [35], and the ARH allele, which is defined as neutral [7], were also observed. "
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    ABSTRACT: Scrapie is a genetically associated neurodegenerative disease caused by the accumulation of an abnormal protein. The aim of this study was to perform genotyping of some scrapie-positive cases in sheep and the flocks they come from and to compare the effect of specific polymorphisms. It is important to examine positive cases in order to determine the possible polymorphism in the PRNP gene and its possible phenotypical appearance. Seventy-nine blood samples and 7 brain samples from scrapie affected flocks were tested. Five flocks of sheep, of different size and breed, were genotyped and the results showed that 3 of the animals in flock 1 had additional polymorphism in codon 138, nucleotide 413. In two of the animals from flock 5 there was homozygous and heterozygous polymorphism in codon 138, position 414. The VRQ allele, which is associated with high susceptibility to scrapie, was found in all the flocks, except flock number 2. Our data showed that the atypical scrapie cases are not associated with polymorphism in codon 141. Additional polymorphism was also observed at codons 137, 138, 151 and 152. Strategies for eradication of scrapie have been employed.
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    • "In contrast, other resistance-associated alleles (M142, R143 and H154) could not be targeted, due to their much lower frequencies in bucks. Furthermore, the H154 allele has been associated with increased susceptibility to atypical scrapie in both sheep and goats [26,27]. Thus, the feasibility of incorporating M142, R143, and H154 alleles into a selective breeding scheme is low. "
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    ABSTRACT: The present study investigates the potential use of the scrapie-protective Q211 S146 and K222 caprine PRNP alleles as targets for selective breeding in Greek goats. Genotyping data from a high number of healthy goats with special emphasis on bucks, revealed high frequencies of these alleles, while the estimated probabilities of disease occurrence in animals carrying these alleles were low, suggesting that they can be used for selection. Greek goats represent one of the largest populations in Europe. Thus, the considerations presented here are an example of the expected effect of such a scheme on scrapie occurrence and on stakeholders.
    Veterinary Research 04/2014; 45(1):43. DOI:10.1186/1297-9716-45-43 · 2.82 Impact Factor
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    • "A. Granato et al. / Small Ruminant Research 113 (2013) 323–328 327 (VRQ frequency close to 18% and 16%, respectively), and by Townsend et al. (2005) in some rare English sheep breeds (Galway and White Face Dartmoor). In the non-VRQ breeds, animals with the ARQ/ARQ genotype are considered to be the most susceptible to classical scrapie, as observed in the Suffolk breed, in Spanish scrapie-affected flocks and in sheep involved in about 200 scrapie outbreaks in Germany (O'Rourke et al., 1997; Acín et al., 2004; Lühken et al., 2007, respectively). All these studies evidenced that sheep with the ARQ/ARQ genotype were at the highest risk of acquiring classical scrapie. "
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    ABSTRACT: This study investigated classical scrapie susceptibility in four native Italian sheep breeds (Lamon, Brogna, Alpagota, Foza) through PrP genotyping. The investigation revealed that the majority of animals overall showed moderate to high susceptibility to classical scrapie. The Lamon and Brogna breeds exhibited the highest frequency of the highly susceptibleVRQ allele (38.1% and 19.3%, respectively), while the Alpagota and Foza had a high frequency of the ARQ allele (85% and 64%, respectively), also considered to confer susceptibility. The Foza breed showed a significantly high frequency (P < 0.01) of the rare ARK allele (9.7%); a similar frequency has never been described before in the literature. This study stresses the importance of genotyping native sheep breeds both to better organize conservation schemes and to assess the risk of contracting classical scrapie. Additionally, the investigated native breeds revealed some characteristics that could be interesting for research purposes. These sheep could in fact be used to investigate the susceptibility of the ARK allele to classical scrapie, but also to determine whether its relatively high frequency is indicative that the origin of the Foza breed differs from the other Venetian sheep breeds.
    Small Ruminant Research 06/2013; 113(2-3):323-328. DOI:10.1016/j.smallrumres.2013.03.009 · 1.13 Impact Factor
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