The susceptibility of sheep to classical scrapie and bovine spongiform encephalopathy (BSE) is mainly influenced by prion protein (PrP) polymorphisms A136V, R154H, and Q171R, with the ARR allele associated with significantly decreased susceptibility. Here we report the protective effect of the amino acid substitution M137T, I142K, or N176K on the ARQ allele in sheep experimentally challenged with either scrapie or BSE. Such observations suggest the existence of additional PrP alleles that significantly decrease the susceptibility of sheep to transmissible spongiform encephalopathies, which may have important implications for disease eradication strategies.

The salivary glands of scrapie-affected sheep and healthy controls were investigated for the presence of the pathological prion protein (PrP Sc ). PrP Sc was detected in major (parotid and mandibular) and minor (buccal, labial, and palatine) salivary glands of naturally and experimentally infected sheep. Using Western blotting, the PrP Sc concentration in glands was estimated to be 0.02 to 0.005% of that in brain. Immunohistochemistry revealed intracellular depositions of PrP Sc in ductal and acinar epithelia and occasional labeling in the lumina of salivary ducts. The presence of PrP Sc in salivary glands highlights the possible role of saliva in the horizontal transmission of scrapie.

Hepatitis E virus (HEV) is an RNA virus causing an acute generally self-limited disease in humans. An increasing number of autochthonous cases linked to zoonotic transmission of HEV genotype 3 have been reported over the last 10 years in Europe. Pigs and wild boars are considered the main reservoirs. The principal route of transmission in Europe is food-borne, linked by direct or indirect evidence to the consumption of raw or undercooked pork products and wild boar meat. In this study, we sampled 92 wild boar (Sus scrofa) livers during active surveillance in five municipalities in Central Italy throughout the hunting season 2016-2017. HEV RNA was detected in 52.2% of liver sampled with prevalence ranging from 0.0% to 65.7%. HEV-positive wild boars were detected in all but one area of hunting. Phylogenetic analysis showed that strains clustered within the two subtypes HEV-3c and HEV-3f and displayed a wide range of phylogenetic diversity. Several strains were circulating in the areas investigated; animals possibly belonging to the same family group hunted by the same team were infected with a unique strain (100% nucleotide identity). As wild animals are a proven source of HEV transmission to humans and pigs, the high prevalence observed (mean 52.2%) poses a question on the risk of consuming raw or undercooked wild boar meat, and thus, this subject deserves further investigations.

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The susceptibility of sheep to scrapie is influenced mainly by the prion protein polymorphisms A136V, R154H, and Q171R/H. Here we analyzed the ability of protein misfolding cyclic amplification (PMCA) to model the genetic susceptibility of sheep to scrapie. For this purpose, we studied the efficiency of brain homogenates from sheep with different PrP genotypes to support PrP Sc amplification by PMCA using an ARQ/ARQ scrapie inoculum. The results were then compared with those obtained in vivo using the same sheep breed, genotypes, and scrapie inoculum.