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

Abstract

Simple SummaryScrapie is a naturally occurring transmissible spongiform encephalopathy of sheep and goats. Polymorphisms in single nucleotides in the coding sequence of the prion protein gene play a major role in relative susceptibility or resistance to classical scrapie. The most recent modification of European Union Regulation 999/2001 (Regulation EU 772/2020) deals with the possible use of genetics in goats for scrapie outbreak management. In this work, sequence analysis of the prion protein gene was performed, with the main aim to obtain information about the genetic variability of eight Italian local populations/breeds and establishing phylogenetic relationships between the breeds/populations. This research could help to promote the adoption of selective breeding programs as a possible future strategy in scrapie control and outbreak prevention. In particular, genomic DNA was extracted from 219 goat whole blood samples and 13 polymorphic sites were observed, giving 24 different alleles. We observed the K222 allele, associated to scrapie resistance, with a mean frequency of 10%. Interestingly, we also described in Italy the circulation of the S146 allele: In particular, S146 only segregated in the Alpine breed at a frequency of 3.7%. This study adds information on genetic variability of the PRNP locus in goat populations/breeds, so contributing to the design of genetic control measure both in scrapie outbreaks and in disease prevention.In goats, as in sheep, genotypes of the prion protein gene (PRNP) can influence animals’ susceptibility to scrapie. Since the polymorphic codons in sheep are well known, a genetic selection plan has been implemented in Europe, in order to reduce the prevalence of susceptible genotypes to scrapie. In Italy, no breeding plan for scrapie resistance in goats has been adopted, yet. Likewise, according to the most recent modification of Regulation EU 999/2001 (Regulation EU 772/2020) of the European Commission (EU), based on all the available experimental and in field data, K222, D146 and S146 polymorphisms could be used as scrapie resistance alleles in genetic management both in scrapie outbreaks and in disease prevention. In order to collect data on the variability of PRNP, the present study aimed to analyze the sequence of the PRNP gene in eight Italian local goat populations/breeds reared in central and southern Italy (Bianca Monticellana, Capestrina, Facciuta della Valnerina, Fulva del Lazio, Garganica, Grigia Ciociara, Grigia Molisana, and Teramana), some of which were investigated for the first time; moreover, two cosmopolitan breeds (Alpine and Saanen) were included. Blood samples were collected from 219 goats. Genomic DNA was extracted from whole blood. DNA was used as template in PCR amplification of the entire PRNP open reading frame (ORF). Purified amplicons have been sequenced and aligned to Capra hircus PRNP. Particularly, the alleles carrying the resistance-related 222 K polymorphism occurred in all populations with a frequency between 2.5% and 12.5%. An additional resistance allele carrying the S146 variant was observed with a frequency of 3.7% only in the Alpine breed. For three of the estimated alleles, we could not establish if the found double polymorphisms in heterozygosis were in phase, due to technical limitations. In this context, in addition to selective culling in scrapie outbreaks according to the European regulation in force, in the future, selection plans could be adopted to deal with scrapie and to control its diffusion, meanwhile paying attention to preserve a high variability of PRNP.