Prions, infectious agents causing transmissible spongiform encephalopathies (TSEs), are composed primarily of the pathogenic form (PrPSc) of the cellular prion protein PrPC. The susceptibility of sheep to scrapie is determined by polymorphisms in the coding region of the prion protein gene (PRNP), mainly at codons 136, 154, and 171. The efficiency of in vitro amplification of sheep PrPSc also seems to be linked to the PrP genotype. PrPSc derived from sheep with V136R154Q171-associated genotypes can be amplified efficiently by protein misfolding cyclic amplification (PMCA) in the presence of additional polyanions such as poly A, but there are no reports that cite ultrasensitive detection of PrPSc derived from sheep of other PrP genotypes. Here we report that sheep PrPSc derived from ARQ and AHQ homozygotes was amplified efficiently by serial PMCA using mouse brain homogenate as a PrPC substrate. ARQ/ARQ PrPSc was detected in infected brain homogenates that were diluted up to 10−10 after five rounds of amplification, and AHQ/AHQ PrPSc was detected in samples diluted up to 10−8 after four rounds of amplification. The interspecies PMCA developed in this study may be useful in the detailed analysis of PrPSc distribution in classical scrapie-infected ARQ and AHQ homozygous sheep.
(Prion Disease Research Center)
References:
Murayama Y. et al (2012) Microbiol. Immunol. 56(8):541-547
