NR AXWB
AU Scolamacchia,F.; Nonno,R.; Vaccari,G.; Esposito,E.; Chiappini,B.; Conte,M.; Morelli,L.; Fazzi,P.; Parisi,C.; Bona,C.; Agrimi,U.; Scavia,G.
TI Scrapie Strains and Prion Protein Genetics in Italian Ovine Population: Epidemiological Surveillance
QU International Conference - Prion 2007 (26.-28.9.2007) Edinburgh International Conference Centre, Edinburgh, Scotland, UK - Book of Abstracts: Epidemiology, Risk Assessment and Transmission P04.74
IA http://www.prion2007.com/pdf/Prion Book of Abstracts.pdf
PT Konferenz-Poster
AB
Susceptibility of sheep to scrapie is influenced by polymorphisms of prion protein (PrP) gene as well as by the scrapie strains. The aim of this study is to describe the results of sheep transmissible spongiform encephalopathies (TSEs) surveillance in Italy, with regard to prion protein genotyping and molecular strain typing, between July 2004 and December 2006. Classical scrapie cases were identified in 109 flocks (128 index and 323 secondary cases) while Nor98 in 23 flocks (24 index and 2 secondary cases). In only one flock both strains were diagnosed (1 index Nor98 and 1 secondary classical strain). The ARQ/ARQ genotype was by far the most dominant (411 cases) in classical scrapie infection, followed by ARQ/AHQ (34), ARQ/VRQ (5), AHQ/AHQ (1) and ARR/ARQ (1). On the whole, a proportion of 99.8% of affected animals carried the wild type PrP allele (ARQ) and 7.1% the AHQ. Polymorphisms other than those at codons 136, 154 and 171, were recorded at codon 141 (L/F) in 4.9% of the sheep carrying the ARQ allele.
As far as Nor98 is concerned, only 29.6% of positive cases carried the ARQ/ARQ genotype. Moreover the ARR/ARQ, ARQ/AHQ, ARR/ARR, ARR/AHQ and ARR/ARH genotypes were present in 33.3%, 18.5%, 11.1%, 3.7% and 3.7% respectively of diseased animals. The amino acid substitution L/F at codon 141 was present in 72.7% of sheep carrying the ARQ allele. Worthy of note is that more than 80% of the Nor98 positive sheep carried either the AF141RQ or the AHQ allele.
Our data suggest that significant differences between classical and atypical scrapie exist concerning the host genetic targeting. In classical scrapie the most affected genotype was the ARQ/ARQ, while in Nor98 cases, a high proportion of sheep carried either the AF141RQ or the AHQ allele.
AD F. Scolamacchia, R. Nonno, G. Vaccari, E. Esposito, B. Chiappini, M. Conte, L. Morelli, P. Fazzi, C. Parisi, U. Agrimi, G. Scavia, Istituto Superiore di Sanità, Italy; C. Bona, Istituto Zooprofilattico Sperimentale del Piemonte, Italy
SP englisch
PO Schottland