Biodiversity and Genetic Polymorphisms Against Scrapie inSopravissanaSheep Breed

Abstract

Scrapie is a neurodegenerative disease affecting ovine and it is one of several transmissible spongiform encephalopathies (TSEs). Scrapie is recognized as two forms -classical and atypical. Susceptibility or resistance to classical scrapie is strongly regulated by the polymorphisms at codons 136, 154 and 171 of the PRNP gene. Genetic role in atypical scrapie has been described at codons 141 and 154, these ones are involved in the occurrence of the disease at different risk degrees. The aim of this study was to assess the allelic and genotypic frequencies in Sopravissana breed, an endangered autochthon breed of central Italy; in addition, the presence and the frequency of potential protective ARQ allele variants able to increase scrapie resistance by preserving a higher variability of PRNP were evaluated. Three alleles (ARQ, ARR and AHQ) and seven genotypes were observed based on codons 136, 154 and 171 with different frequencies. Moreover, the entire coding sequence of prion protein (PRNP) of the ARQ/ARQ was sequenced; two non-synonymous L141F (23.8%) and H143R (16.7%), also two synonymous polymorphisms (codons 231 and 237) were found. The results showed that the ARQ/ARQ sheep should be considered as a genetic class, which may potentially include animals with different scrapie susceptibility because of the presence of additional polymorphisms. This may allow the application of alternative strategies for breeding programmes in this endangered breed.

Analysis of differences in prion protein gene (PRNP) polymorphisms between Algerian and Southern Italy's goats

“…In Puglia, another region of South Italy, an ARR frequency up to 50% has been detected in sheep (Martemucci et al 2015). In central regions, studies on goat and sheep have reported a frequency of 7% for K222 in Umbria and Marche (Biagetti et al 2016) and 32% of the resistant allele ARR has been detected in a native sheep breed (Curcio et al 2015).…”

PRNP Polymorphisms in Eight Local Goat Populations/Breeds from Central and Southern Italy

“…In sheep, three polymorphic codons of the PRNP (codons 136, 154, and 171) give rise to five main different alleles, namely VRQ, ARQ, AHQ, ARH, and ARR (defined with the IUPAC amino acid codes). The VRQ/VRQ, VRQ/ARQ, and ARQ/ARQ genotypes are associated with high susceptibility to classical scrapie [ 12 ], while the ARR-containing genotypes, with the exception of VRQ/ARR, have been associated with various levels of resistance to disease [ 13 ]. On this basis, according to European Union Decision 2003/100/EC (EU 2003) [ 14 ], a selection breeding program to increase the frequency of the resistance-associated ARR allele in sheep populations has been adopted by each member state in the European Community.…”

Genetic variability following selection for scrapie resistance in six autochthonous sheep breeds in the province of Bolzano (northern Italy)

“…As shown in most Italian (Curcio et al, 2015;Granato et al, 2013;Kaam, Vitale, Portolano, Vitale, & Caracappa, 2005) and European breeds (Álvarez et al, 2009;Cubric Curik et al, 2010;Drögemüller, Leeb, & Distl, 2001;Garcia-Crespo et al, 2004;Goldmann, Baylis, Chihota, Stevenson, & Hunter, 2005;Gorjanc, Plohl, & Kompan, 2008;Hurtado et al, 2002;Lühken, Lipsky, Peter, & Erhardt, 2008;Sipos, Kraus, Schmoll, Achmann, & Baumgartner, 2002;Thorgeirsdottir, Sigurdarson, Thorisson, Georgsson, & Palsdottir, 1999), the predominant PRNP allele across all six breeds was ARQ, which was present in more than a half of the entire population analysed, and particularly in the TS breed (66%), as shown by Sipos et al (2002) in Austrian sheep breeds. Since ARQ is considered the wild-type ancestral allele of PRNP (Drögemüller et al, 2001), we easily expected that it was more present in this breed, because it is the oldest of the ovine breeds present in the Tyrol area (http:// www.fao.org/dad-is/en/).…”