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From: TSS (216-119-144-36.ipset24.wt.net)
Subject: Low frequency of the scrapie resistance-associated allele and presence of lysine-171 allele of the prion protein gene in Italian Biellese ovine breed
Date: October 1, 2004 at 2:09 pm PST

-------- Original Message --------
Subject: Low frequency of the scrapie resistance-associated allele and presence of lysine-171 allele of the prion protein gene in Italian Biellese ovine breed
Date: Fri, 1 Oct 2004 15:14:06 -0500
From: "Terry S. Singeltary Sr."
Reply-To: Bovine Spongiform Encephalopathy
To: BSE-L@UNI-KARLSRUHE.DE


##################### Bovine Spongiform Encephalopathy #####################

Low frequency of the scrapie resistance-associated allele and
presence of lysine-171 allele of the prion protein gene in Italian
Biellese ovine breed

P. L. Acutis1, L. Sbaiz1, F. Verburg2, M. V. Riina1, G. Ru1, G. Moda3,
M. Caramelli1 and A. Bossers2

1 CEA (Centro di referenza per le Encefalopatie Animali), Istituto
Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Via
Bologna 148, 10154 Turin, Italy
2 Central Institute for Animal Disease Control (CIDC-Lelystad), PO Box
2004, 8203 AA Lelystad, the Netherlands
3 Regione Piemonte, Direzione di Sanità Pubblica, Corso Stati Uniti 1,
10128 Turin, Italy

Correspondence
P. L. Acutis
pierluigi.acutis@izsto.it

Frequencies of polymorphisms at codons 136, 154 and 171 of the prion
protein (PrP) gene were studied in 1207 pure-bred and cross-bred Italian
Biellese rams, a small ovine breed of about 65 000 head in Italy. Aside
from the five most common alleles (VRQ, ARQ, ARR, AHQ and ARH), the rare
ARK allele was also found, with the highest frequency reported so far in
an ovine breed (2·5 %). ARK/--- genotypes had a total frequency of 4·9
%. The resistance-associated ARR allele was seen at a low frequency (8·3
%). Only 1·4 % of animals examined had a resistant ARR/ARR PrP genotype.
Semi-resistant (ARR/ARQ, ARR/ARH and ARR/AHQ) PrP genotypes had a total
frequency of 12·6 % and PrP genotypes that are associated with high
scrapie susceptibility (e.g. VRQ/VRQ and ARQ/ARQ) had a total frequency
of 81·1 %. Statistical analysis comparing PrP allele frequencies between
pure-bred and cross-bred animals showed that the ARR allele occurred at
a significantly lower frequency in pure-bred rams. Furthermore,
comparison of PrP allele frequencies between pure-bred rams over
18 months of age and those below 18 months of age showed a significant
decrease in the ARR allele in breeding rams over 18 months of age. Based
on these results, breeding for scrapie resistance in the Biellese breed
will have to take into account the low frequency of the ARR allele,
which also seems to be subject to negative selection by farmers. Further
investigation is required to understand whether the ARK allele is also
associated with resistance to transmissible spongiform encephalopathies.

http://vir.sgmjournals.org/

TSS

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