Cervid to human prion transmission

 描述（由申请人提供）：朊病毒病是可传播的，并且总是致命的。慢性消耗性疾病（CWD）是一种影响鹿、麋鹿和驼鹿的朊病毒疾病，目前已成为一种广泛和不断扩大的流行病，影响美国22个州和加拿大2个省。慢性消耗病在北美造成最严重的人畜共患朊病毒传播风险，因为大量鹿肉消费（仅在美国每年就有超过600万只鹿/麋鹿被猎杀和消费），受慢性消耗病影响的鹿科动物的肌肉和其他组织/液体中存在显著的朊病毒感染性，并且通常只有家人和朋友消费受影响的动物导致个体暴露于慢性消耗病。然而，我们仍然不知道CWD朊病毒是否可以在大脑或外周组织中感染人类，或者临床/无症状的CWD人畜共患病是否已经发生，并且我们没有可靠地检测人类CWD感染的文章。我们假设：（1）经典CWD朊病毒株可在脑和外周淋巴组织中以低水平感染人类;（2）鹿-人传播屏障依赖于鹿朊病毒株，并受宿主（人）朊病毒蛋白（PrP）一级序列的影响;（3）可建立可靠的试验来检测人类CWD感染;（4）CWD已传播至人类。我们将使用转基因（Tg）小鼠模型和互补的体外方法在4个目标中测试这些假设。目的1将证明经典的CWD菌株可以感染人类的大脑或外周淋巴组织在低水平进行系统的生物测定，在一组“人源化”Tg小鼠品系表达常见的人类PrP变异体使用的CWD分离物在不同的剂量和途径。还将为目标3生成实验性“人体慢性消耗病”样本。目的2将利用与目的1相同的人源化Tg小鼠品系，通过检查和比较几种非典型/不寻常CWD分离株/菌株以及来自其他物种的适应了鹿PrP序列的几种朊病毒菌株的传播效率和表型，检验鹿-人朊病毒传播屏障依赖于朊病毒菌株并受宿主（人）PrP序列影响的假设。目标3将通过详细检查目标1-2产生的现有和未来实验性“人类CWD”样本的临床、病理、生化和体外接种特性，并将其与常见的散发性人类克雅氏病（sCJD）朊病毒的临床、病理、生化和体外接种特性进行比较，建立检测和监测人类CWD感染的可靠论文。目标4将尝试通过检查美国和加拿大食用来自于CWD流行地区鹿肉的受朊病毒影响的人类受试者的大量脑样本，利用目标3中确立的标准和论文，检测临床CWD影响的人类病例。 本研究的发现将极大地促进我们对鹿朊病毒在人类中传播的潜力和特征的理解，建立可靠的CWD人畜共患病论文，并可能发现首例CWD感染人类的病例。

 DESCRIPTION (provided by applicant): Prion disease is transmissible and invariably fatal. Chronic wasting disease (CWD) is the prion disease affecting deer, elk and moose, and it is a widespread and expanding epidemic affecting 22 US States and 2 Canadian provinces so far. CWD poses the most serious zoonotic prion transmission risks in North America because of huge venison consumption (>6 million deer/elk hunted and consumed annually in the USA alone), significant prion infectivity in muscles and other tissues/fluids from CWD-affected cervids, and usually high levels of individual exposure to CWD resulting from consumption of the affected animal among often just family and friends. However, we still do not know whether CWD prions can infect humans in the brain or peripheral tissues or whether clinical/asymptomatic CWD zoonosis has already occurred, and we have no essays to reliably detect CWD infection in humans. We hypothesize that: (1) The classic CWD prion strain can infect humans at low levels in the brain and peripheral lymphoid tissues; (2) The cervid-to-human transmission barrier is dependent on the cervid prion strain and influenced by the host (human) prion protein (PrP) primary sequence; (3) Reliable essays can be established to detect CWD infection in humans; and (4) CWD transmission to humans has already occurred. We will test these hypotheses in 4 Aims using transgenic (Tg) mouse models and complementary in vitro approaches. Aim 1 will prove that the classical CWD strain may infect humans in brain or peripheral lymphoid tissues at low levels by conducting systemic bioassays in a set of "humanized" Tg mouse lines expressing common human PrP variants using a number of CWD isolates at varying doses and routes. Experimental "human CWD" samples will also be generated for Aim 3. Aim 2 will test the hypothesis that the cervid-to-human prion transmission barrier is dependent on prion strain and influenced by the host (human) PrP sequence by examining and comparing the transmission efficiency and phenotypes of several atypical/unusual CWD isolates/strains as well as a few prion strains from other species that have adapted to cervid PrP sequence, utilizing the same panel of humanized Tg mouse lines as in Aim 1. Aim 3 will establish reliable essays for detection and surveillance of CWD infection in humans by examining in details the clinical, pathological, biochemical and in vitro seeding properties of existing and future experimental "human CWD" samples generated from Aims 1-2 and compare them with those of common sporadic human Creutzfeldt-Jakob disease (sCJD) prions. Aim 4 will attempt to detect clinical CWD-affected human cases by examining a significant number of brain samples from prion-affected human subjects in the USA and Canada who have consumed venison from CWD-endemic areas utilizing the criteria and essays established in Aim 3. The findings from this proposal will greatly advance our understandings on the potential and characteristics of cervid prion transmission in humans, establish reliable essays for CWD zoonosis and potentially discover the first case(s) of CWD infection in humans.