Ovine prion  protein genotype frequencies in northwestern China.
Anti-scrapie  breeding programs have been initiated to screen for scrapie-resistant sheep  based on ovine prion protein gene (PRNP) genotypes at codons 136, 154 and 171  in many countries, especially European Union member states. However,  investigation of sheep PRNP genotypes is limited in China, despite the large  number of sheep breeds. We analyzed 432 sheep of five different breeds from  farms in northwestern China, using PCR-single-strand conformational  polymorphism analysis (PCR-SSCP); the corresponding haplotypes of different  PRNP alleles were cloned. PRNP allele genotyping was done by amplification  refractory mutation system-PCR (ARMS-PCR), according to the haplotype clones of  each PRNP allele. The validity of ARMS-PCR was checked by PCR-SSCP. Another 325  unknown PRNP genotypes of other sheep breeds were analyzed according to the  established ARMS-PCR. Genotype frequencies of 757 sheep were analyzed with  these two methods to evaluate susceptibility to scrapie in northwestern China. Relevant  mutations were also detected at other sites. Both methods were effective for  ovine PRNP allele genotyping, and the results of the analysis completely  coincided. Scrapie-resistant genotypes were found to be uncommon, indicating a  high risk for ovine scrapie in northwest China. In addition to codons 136, 154  and 171, we found numerous new mutations; nearly half of them were previously  unreported. These sheep populations have a high degree of polymorphism at the  PRNP locus.
College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, China.
C-L
CL
Zhao
R
R
Wu
L
L
Liu
F-D
FD
Li
X-L
XL
Zhang
C
C
Wang
F
F
Wang
X-L
XL
Diao
H-W
HW
Guan
X
X
Wang
L
L
Zhou
D000818:Animals; D002681:China; D005838:Genotype; D016133:Polymerase Chain Reaction; D018807:Polymorphism, Single-Stranded Conformational; D011328:Prions / Q000235:genetics*; D034561:Sheep, Domestic / Q000235:genetics*
D011328:Prions