ABSTRACT. Polymorphism of the PrP gene is a primary factor influencing susceptibility and incubation period in natural and experimental scrapie in sheep and goats. Polymorphisms of the caprine PrP gene in Japan were examined in 118 goats. Eight allelic variants and 19 genotypes were obtained. Amino acid polymorphisms were observed at 7 codons: 102, 142, 143, 240, 127, 146 and 211 (the latter 3 are novel polymorphisms). The polymorphisms at codons 142M and 143R, which are associated with the resistance to scrapie, were relatively rare in the present study. Thus, the present results provide information about the caprine PrP gene that may be useful for assessing the risk of goat scrapie. KEY WORDS: goat, polymorphism, PrP.J. Vet. Med. Sci. 67(3): 321-323, 2005 Scrapie is a fatal and infectious neurodegenerative disease that occurs in sheep and goats. Like bovine spongiform encephalopathy (BSE) in cattle and Creutzfeld-Jakob disease (CJD) in humans, scrapie is a transmissible spongiform encephalopathy (TSE). TSEs are characterized by accumulation of an abnormal isoform (PrP Sc ) of a normal cellular prion protein (PrP C ) in the central nervous system [12]. Among animals with natural or experimental scrapie, there is considerable variation in susceptibility and incubation period, even when the animals are exposed to the same infectious agent simultaneously [1,4,9]. Studies have shown that interaction between the scrapie strain and the PrP genotype in the affected animals plays a primary role in differences in infectivity [4,8]. Polymorphisms of the open reading frame (ORF) of the cellular PrP gene significantly influence the incidence of natural scrapie [1,9]. Amino acid polymorphisms of the sheep PrP gene have been observed at the following codons: 112 (M→T), 136 (A→V), 137 (M→T), 138 (S→N), 141 (L→F), 151 (R→C), 154 (R→H), 171 (Q→H or Q→R), 176 (K→N), and 211 (R→Q). The amino acid polymorphism at codon 171 is strongly associated with incubation period in many breeds of sheep [1,4,7,9,10,14].Goats as well as sheep are natural hosts for scrapie. The clinical signs of affected goats are slightly different from those of sheep, but the observed variation of incubation period is similar to that described for sheep [11,14]. Studies have shown amino acid polymorphisms of the caprine PrP gene at the following codons: 21 (V→A), 23 (L→P), 49 (G→S), 102 (W→G), 142 (I→M), 143 (H→R), 154 (R→H), 168 (P→Q), 220 (Q→H) and 240 (S→P) [2,3,5,6,11].In Japan, caprine scrapie has not yet been observed, although occurrence of sheep scrapie in Japan has been reported [10,13]. In the present study, we investigated polymorphisms of the PrP gene in goats raised in Japan, to obtain genetic information for use in assessing the risk of the occurrence of scrapie in goats. A total of 118 samples (48 tonsillar samples and 70 blood samples) were collected from healthy goats in Japan (Table 1). The 48 tonsillar samples were collected from Honshu Island, the Hachijo Islands and Hokkaido Island for TSE surveillance. The 70 blood samples were coll...