No abstract

Scrapie resistance or susceptibility in sheep is associated with single nucleotide polymorphisms (SNPs) at codons 136, 154, and 171 of the prion protein gene ( PRNP). In addition, phenylalanine mutation at codon 141 has been recognized as a risk factor for atypical scrapie. In contrast, K222, D146, and S146 alleles confer genetic resistance to classical scrapie in goats. High-throughput genotyping technologies would provide significant benefits in scrapie eradication plans. The ability to resolve oligonucleotides varying in mass by less than a single nucleotide makes MALDI-TOF mass spectrometry (MS) a suitable platform for PRNP genotyping. We evaluated the commercial Myriapod scrapie kit (Diatech Pharmacogenetics), associated with a highly automated processing platform incorporating MALDI-TOF MS technology, to detect SNPs at codons 136, 154, 171, 141, and 222 of small ruminant PRNP. The Myriapod scrapie kit was accredited according to UNI CEI EN ISO/IEC 17025. We present the genotyping results of 10,960 sheep in Sicily and 1,822 goats in Sicily and Calabria (southern Italy) tested during 2017. We found a high frequency (43.9%) of the protective ARR allele in sheep and a promising 12.3% of the resistant K222 variant in goats. This efficient and high-throughput method is suitable for extensive PRNP genotyping, as requested in the European scrapie eradication plan.

The most representative sheep in Sicily are Belicina, Comisana, Pinzirita, Barbaresca and the crossbred derived sheep from all this species. In this study, the allelic frequencies of the Sicilian sheep population were investigated. It currently represents the best way to determine the genetic identity and/or family even with limited amounts of sample or when the DNA is degraded. The aim of the study was to provide a reference data bank and to evaluate a microsatellite panel for pedigree analysis as suggested by the International Society for Animal Genetics (ISAG). There are various studies on European sheep, but few datasets were developed on the population of Sicilian sheep. The reference database will include allele frequencies at each locus and will determine genetic parameters for Sicilian ovine species selection. Our results indicated that Hardy Weinberg equilibrium was not always maintained. These results could be explained by a non-random mating. The database is useful to investigate the relationship, the parentage the meat traceability and in disease control programs. The standardized panels of allele frequencies represent a molecular fingerprinting characterizing the subjects with very high definition level and can be useful to control all the livestock. The parentage identification could be important for the veterinary police to investigate the theft or the animal substitutions in the Sicilian farms.