Department of Epidemiology, Crisis organisation and Diagnostics, Central Veterinary Institute of Wageningen UR, P,O, Box 65, 8200 AB Lelystad, the Netherlands.
Vet Res. 2011 Jan 11;42(1):5. doi: 10.1186/1297-9716-42-5.
Susceptibility to scrapie, a transmissible spongiform encephalopathy in sheep, is modulated by the genetic make-up of the sheep. Scrapie control policies, based on selecting animals of resistant genotype for breeding, have recently been adopted by the Netherlands and other European countries. Here we assess the effectiveness of a breeding programme based on selecting rams of resistant genotype to obtain outbreak control in classical scrapie-affected sheep flocks under field conditions. In six commercially-run flocks following this breeding strategy, we used genotyping to monitor the genotype distribution, and tonsil biopsies and post-mortem analyses to monitor the occurrence of scrapie infection. The farmers were not informed about the monitoring results until the end of the study period of six years. We used a mathematical model of scrapie transmission to analyze the monitoring data and found that where the breeding scheme was consistently applied, outbreak control was obtained after at most four years. Our results also show that classical scrapie control can be obtained before the frequency of non-resistant animals is reduced to zero in the flock. This suggests that control at the national scale can be obtained without a loss of genetic polymorphisms from any of the sheep breeds.
绵羊传染性海绵状脑病（羊痒病）的易感性受绵羊遗传构成的影响。最近，荷兰和其他欧洲国家采取了基于选择抗性基因型动物进行繁殖的羊痒病控制策略。在这里，我们评估了一种基于选择抗性基因型公羊的繁殖计划在田间条件下获得经典羊痒病感染羊群爆发控制的有效性。在遵循这一繁殖策略的六个商业运营羊群中，我们使用基因分型监测基因型分布，并通过扁桃体活检和死后分析监测羊痒病感染的发生。直到六年研究期结束，农民才被告知监测结果。我们使用羊痒病传播的数学模型分析监测数据，发现只要繁殖计划始终得到执行，最多四年后即可获得爆发控制。我们的研究结果还表明，在羊群中不再存在非抗性动物之前，可以获得经典羊痒病的控制。这表明，在不丧失任何绵羊品种遗传多态性的情况下，可以在国家范围内获得控制。
