Proceedings of 5th International Congress of Veterinary Virology 1 NATURAL SCRAPIE AND PrP GENOTYPE IN A FLOCK OF MASSESE SHEEP IN ITALY

Introduction Scrapie is a fatal neurodegenerative disease in sheep and goats that occurs naturally and belongs to the group of disorders known as tranmissible spongiform encephalopathies (TSE) or Prion diseases. Prion diseases manifest as infectious, sporadic and/or inherited disorders. They are characterised by the accumulation of protease-resistant isoform of the host encoded prion protein (PrP) in the brain of affected animals and humans. In Italy, scrapie has sporadically been observed since 1977. Recently the disease has gained more attention following a sudden increase of reported cases starting from 1996, especially in goats, probably as a consequence to the use of contaminated vaccine against contagious agalactia, which raise the hypothesis of a iatrogenic origin of the infection (1). Several polymorphisms in the gene of PrP are associated with the incidence, susceptibility and pathology of the disease. In particular, amino acid codons 136, 171 and to a minor extent 154, seem to be mostly involved in determining scrapie susceptibility of sheep. This finding has been use to write a "Guidance on the use of PrP genotyping as an aid to the control of clinical scrapie" (4). In spite of the well established correlation between occurrence of scrapie in sheep and their genotype, only few genetic studies have been carried out on the several breeds of sheep reared in Italy. Here, we report on a case of scrapie in a flock of Massese sheep which was found to be affected by scrapie during an epidemiological survey on neurological disease of sheep carried out on 23 flocks in Emilia Romagna region during 1996 (5). The flock of Massese sheep, a breed quite common in the regions of central Italy, was founded using sheep coming from two regions: a group belonged to a flock in Emilia Romagna and the second was moved from a flock from Tuscany. No data are available from the original flocks. Interestingly, overt cases of scrapie were only observed in the first group while the latter was claimed by the farmer as scrapie-free since no cases has never been observed. In spite of the limited information available, the data show that sheep homozygous glutamine at codon 171 (QQ171) are highly susceptible to scrapie.