Prion protein (PrP) gene polymorphisms in Small East African and Norwegian white goats

摘要

The relationship between caprine PrP gene polymorphisms and susceptibility or resistance to scrapie has been actively investigated in recent years. The ORF of the PrP gene is highly variable in different breeds of goats. We studied the PrP gene polymorphisms in 240 goats comprising of the Norwegian white (NW), Small East African goats (SEA) and their crosses. A total of seven distinct polymorphic sites with amino acid substitutions were identified. We discovered two novel polymorphisms; Al 16V and Q220L in SEA goats and NW respectively. These mutations are reported here for the first time. The Al 16V allele was found at low frequency only in the SEA goats. Distribution of this allele in other goat breeds and its role in determining susceptibility or resistance to scrapie is unknown. Five polymorphisms of amino acids at codons: 32(G -> Stop), 142(I -> M), 146(N -> S), 211(R Q) and 240(P S) were also observed as previously described in other studies. Two silent mutations at codons 42(ccg -> cca) and 138(agt -> agc) were also detected, and both were linked to 240(P S) in most of the animals. The majority of SEA goats seem to have little variation in their PrP gene as compared to the NW and crossbred goats. The coding region of the PrP gene of the SEA goats is closer to 'wild type' form. In this study, the mutations linked with susceptibility of goats to scrapie and other TSEs were observed at higher frequency while those associated with some levels of resistance occurred at lower frequency. Further studies on the implications of the mutations of the caprine PrP gene to susceptibility and resistance status to scrapie and other TSEs worldwide are of importance. (C) 2014 Elsevier B.V. All rights reserved