NR AWLK
AU Orge,L.; Silva,J.; Machado,C.; Simas,J.P.
TI Prnp genotype distribution in atypical scrapie cases in Portugal, including the association with the recently reported leucine haplotype (ALQ)
QU International Conference - Prion 2006: Strategies, advances and trends towards protection of society - 3.10.-6.10.2006, Torino, Italy, Lingotto Conference Centre - Poster sessions GEN-21
PT Konferenz-Poster
AB
Until March 2006, all the cases of portuguese sheep with PrPres deposition in the central nervous system have shown a different pattern of distribution in the brainstem as well as a distinct electrophoretic profile from that observed for scrapie. The PrPres electrophoretic profile has been of the same range and pattern as that described for Nor 98.
This work reports the Prnp genotype distribution in sheep confirmed with atypical scrapie (n=126) in Portugal comparing with the Prnp genotype profile in Portuguese sheep population.
For Prnp genotyping at codons 136, 141, 154 and 171, genomic DNA extracted from frozen brainstem and ear tissues was subjected to PCR amplification. Following purification, PCR products were then submitted to automated cycle sequencing using an ABI Prism 377 DNA sequencer (Perkin Elmer). The majority of the cases were homozygous for ARQ followed by genotypes rarely associated with scrapie that are included in the National Scrapie Plan (NSP) types 2 and 1. Those genotypes were also the predominant genotypes determined in both Portuguese pure sheep breeds and random sampled ovine animals. The VRQ/XXX genotypes (NSP types 4 and 5) highly susceptible to classical scrapie have not been identified, as yet, in any of the atypical scrapie cases, despite their presence in portuguese sheep, albeit at low frequency. Notably, the recent described haplotype ALQ was also detected in an atypical scrapie positive case combined with the ARQ allele. This new haplotype was never reported in Portuguese sheep.
The apparent absence of classical scrapie in Portuguese sheep population and the Prnp haplotypes associated with atypical scrapie, suggest a phenomenon of natural selection in this region of Europe. These data should be taken into account in the current EU sheep-breeding programme for selection of non-susceptible haplotypes.
AD L. Orge, J. Silva, C. Machado: Laboratório Nacional de Investigação Veterinária, Unidade de BSE, Lisbon, Portugal; J.P. Simas: Instituto de Microbiologia e Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, e Instituto Gulbenkian de Ciência, Oeiras, Portugal
SP englisch
PO Italien