Ante-mortem detection of chronic wasting disease in recto-anal mucosa-associated lymphoid tissues from elk (Cervus elaphus nelsoni) using real-time quaking-induced conversion (RT-QuIC) assay: A blinded collaborative study

Prion diseases are transmissible spongiform encephalopathies (TSEs) characterized by fatal, progressive neurologic diseases with prolonged incubation periods and an accumulation of infectious misfolded prion proteins. Antemortem diagnosis is often difficult due to a long asymptomatic incubation period, differences in the pathogenesis of different prions, and the presence of very low levels of infectious prion in easily accessible samples. Chronic wasting disease (CWD) is a TSE affecting both wild and captive populations of cervids, including mule deer, white-tailed deer, elk, moose, muntjac, and most recently, wild reindeer. This study represents a well-controlled evaluation of a newly developed real-time quaking-induced conversion (RT-QuIC) assay as a potential CWD diagnostic screening test using rectal biopsy sections from a depopulated elk herd. We evaluated 69 blinded samples of recto-anal mucosa-associated lymphoid tissue (RAMALT) obtained from USDA Veterinary Services. The results were later un-blinded and statistically compared to immunohistochemical (IHC) results from the USDA National Veterinary Services Laboratories (NVSL) for RAMALT, obex, and medial retropharyngeal lymph node (MRPLN). Comparison of RAMALT RT-QuIC assay results with the IHC results of RAMALT revealed 92% relative sensitivity (95% confidence limits: 61.52–99.8%) and 95% relative specificity (95% confidence limits: 85.13–99%). Collectively, our results show a potential utility of the RT-QuIC assay to advance the development of a rapid, sensitive, and specific prion diagnostic assay for CWD prions.     

兔延髓闩部尼可刹米敏感区的研究

本实验用家兔51只,乌拉坦麻醉(0.5g/kg体重),切断双侧颈迷走神经,三碘季铵酚制动(4mg/kg体重),用人工呼吸维持通气。在延髓闩部局部给予尼可剎米,观察膈神经和延髓吸气性单位放电的变化。结果如下:1.在延髓闩部表浅脑组织局部给予微量尼可剎米后,膈神经放电及孤束核区吸气性单位放电的节律都明显增快。2.在延髓闩部给予生理盐水,缓冲液(pH=6.35),或咖啡因、吗啡等药物,对膈神经放电都无明显影响。用的卡因处理闩部或将闩部损毁后,尼可剎米的上述效应不再出现。以上结果提示延髓闩部对尼可剎米有特殊的敏感性。