Following a request from the European Commission, EFSA was asked to provide scientific and technical assistance on the provisional results of a study on genetic resistance to Classical scrapie in goats in Cyprus. The study was performed by the European Union Reference Laboratory for Transmissible Spongiform Encephalopathies (TSE EURL) and the Cypriot Veterinary Services (CVS). In 2006/2007 a pilot project on this topic was undertaken in Cyprus. In 2009 EFSA was asked by the European Commission to evaluate the results from the pilot project and, later, a draft protocol for additional studies. A final protocol for new studies to be carried out in Cyprus was subsequently agreed by the European Commission, the TSE EURL and the CVS. Implementation of the protocol started at the end of 2009 (EURL/Cypriot study).
This EFSA Scientific Report reviews and discusses the provisional results of the EURL/Cypriot study as concerns the four research areas implemented: i) effect of D146 and S146 PRNP alleles on the individual susceptibility to Classical scrapie infection; ii) TSE agent diversity and resistance/susceptibility associated with the D146 and S146 alleles; iii) effect of D146 and S146 PRNP alleles on Classical scrapie pathogenesis; and iv) capacity for selection and diffusion of the PRNP allele in the Cypriot goat population.
It is concluded that the provisional results obtained in the study further support the lower susceptibility to Classical scrapie in goats carrying the D146 and S146 alleles compared to wild type (N146N) goats. The results from intracerebral challenge are not compatible with a level of resistance as high as the one observed in sheep carrying the ARR allele or in goats carrying the K222 allele. Final results from the oral challenge will be crucial in determining the level of resistance associated with the D146 and S146 alleles.
Furthermore, it is concluded that the provisional results obtained in the study are compatible with the possibility to use the D146 and S146 alleles to build a genetic strategy to control and eradicate Classical scrapie in goats in Cyprus. However, the success of such a strategy will be determined by the level of resistance associated with the D146 and S146 alleles against infection with all the different TSE agents proved to be circulating in Cyprus, which at this stage of the EURL/Cypriot study remains to be definitively assessed. In addition, as compared to the results of the model developed in the study, it is concluded that the efficiency of the implementation in the field of a breeding strategy selecting for the D146 and S146 alleles may be lower due to potential practical constraints related to the management of genetic diversity, to the selection for production and health traits and to the need of moving animals for breeding purposes in Cyprus.
The Scientific Report formulates recommendations on aspects that may be considered when completing the study. In particular, approaches are suggested for characterising TSE isolates from Cypriot goats and estimating the potential level of resistance towards them associated to the D146 and S146 alleles. Suggestions are made about possible issues to be considered in the analysis of the capacity for selection and diffusion of the alleles of interest. Finally, it is indicated that introgression of the K222 allele into the Cypriot goat Damascus breed could be considered as a possible alternative to selection for the D146 and S146 alleles in case this solution was not suitable.