Again a report appeared to show the resistance linked to amino acid 222 lysine (222K) in goat prion protein (PrP, gene PRNP) by using experimental scrapie challengs in goats as previosuly performed with scrapie from Italy (link). However, this time not only the 222K allele but also other potentially susceptibility linked PrP polymorphisms were tested, like 142M, 154H, 211Q. In this report using scrapie from France, Lacroux (from the INRA institutes, Toulouse) and others did not only perform challenges via the brain, but also through the mouth. Both routes showed the high level of protection by the 222K allele, both in the heterozygous (Q/K) and the homozygous (K/K) carriers.
They also demonstrate that 154H, 211Q, and 222K PRNP allele carriers are all resistant to scrapie infection following oral exposure. However, in comparison to the wild type animals, the 154H and 211Q allele carriers displayed only moderate increases in the incubation period following challenge through the brain. In the latter condition of challenge, heterozygous 222K and a small proportion of homozygous 222K goats also developed the disease, but with incubation periods that were 4 to 5 times longer than those in WT animals. These results support the contention that the 222K goat prion protein variant provides a strong but not absolutely protective effect against classical scrapie.