Study of CWD Deer and Elk Prion Disease in Nonhuman Primates

为了研究CWD跨物种传播的可能性，用感染CWD的鹿或麋鹿的脑组织材料经口或脑内感染两种非人类灵长类动物松猴和食蟹猴。在2011财年结束时，13只脑内感染的松鼠猴中有13只出现了临床神经症状，并经脑部生化和病理检查证实患有普恩病毒病。九只口服感染的松鼠猴也患上了疾病，其中两只仍然没有症状。在2011财年，两只受感染的食蟹猴因与典型的普恩病毒疾病症状无关的原因被实施安乐死，并对普恩病毒病进行了检测。到目前为止，无论采用何种接种途径，食蟹猴都没有患上普里恩病(所有猕猴都是在8年前接种的)。对其余猴子的观察将继续进行。 在2008财年，另外四只食蟹猴和松鼠猴被接种了从感染CWD的松鼠猴脑匀浆中提取的脑匀浆，以评估CWD适应非人类灵长类宿主的能力。在2010财年期间，接种适应CWD的松鼠猴的两只松鼠猴都发生了疾病。这种接种剂的潜伏期要快得多，临床症状略有不同，表明适应了新的宿主或更高滴度的接种剂。从一只松鼠猴衍生的CWD成功地传给了另一只松鼠猴，证实了普恩病毒的存在。这一确认很重要，因为相同的松鼠猴CWD疫苗在表达人或鹿普恩蛋白的转基因小鼠中不会引起疾病，也没有在任何仍在研究中的食蟹猴中引起疾病。 为了进一步测试CWD对任何一种人类嗜性的适应性，我们在2011财年将临床患病的第二代松鼠猴子的材料接种到表达人Pron蛋白的转基因小鼠中。在2012财年期间，这些转基因小鼠被实施了安乐死，并进行了普恩病毒病检测。在第二代研究中，所有小鼠的普恩病毒感染都是阴性的。 缺乏对“人源化”小鼠的传播是令人鼓舞的数据，这些数据支持CWD可能不会感染人类的结论。 除了测试受感染的松鼠猴子的大脑外，我们还在评估受感染的松鼠猴子的血液中是否存在普恩病毒。在2012财年结束时，这些猴子中没有一只表现出任何疾病迹象。

To study the possibility of cross-species transmission of CWD, two species of nonhuman primates, squirrel monkeys and cynomologus macaques, were infected orally or intracerebrally with brain material derived from CWD affected deer or elk. At the conclusion of FY11 thirteen of thirteen intracerebrally infected squirrel monkeys had developed clinical neurological signs and were confirmed by biochemical and pathological testing of brain to have a prion disease. Nine orally infected squirrel monkeys have also developed disease, two remain asymptomatic. During FY11 two infected cynomologus macaques were euthanized for reasons unrelated to typical prion disease signs and tested for prion disease. To this point no cynomologus macaques have developed prion disease regardless of inoculation route (all macaques were inoculated > 8 years ago). Observations on the remaining monkeys will continue. During FY08 four additional cynomologus macaques and squirrel monkeys were inoculated with brain homogenates derived from a CWD infected squirrel monkey to evaluate the ability of CWD to adapt to a nonhuman primate host. During FY10 both squirrel monkeys inoculated with squirrel monkey adapted CWD developed disease. The incubation period from this inocula was much faster and clinical signs were slightly different suggesting adaptation to a new host or a higher titer of inocula. The successful passage of CWD derived from a squirrel monkey into additional squirrel monkeys confirms the presence of prion infectivity. This confirmation was important since the same squirrel monkey CWD inocula did not cause disease in transgenic mice expressing human or deer prion protein and has not caused disease in any of the cynomolgus macaques still under study. To further test adaptation of CWD to either a human tropism we inoculated material from the clinically ill second passage squirrel monkeys into transgenic mice expressing human prion protein during FY11. During FY12 these transgenic mice were euthanized and tested for prion disease. All of the mice in this second passage study were negative for prion infection. The lack of transmission to the "humanized" mice is encouraging data that supports the conclusion that CWD will likely not infect humans. In addition to testing infected squirrel monkey brain we are also evaluating blood from infected squirrel monkeys for the presence of prion infectivity. None of these monkeys have shown any signs of disease at the close of FY12.