Thomas Nancy, White C LeAnn, Saliki Jeremiah, Schuler Krysten, Lynch Deanna, Nielsen Ole, Dubey J P, Knowles Susan
US Geological Survey, National Wildlife Health Center, 6006 Schroeder Road, Madison, Wisconsin 53711, USA.
Athens Veterinary Diagnostic Laboratory, University of Georgia, 501 D. W. Brooks Drive, Athens, Georgia 30602, USA.
J Wildl Dis. 2020 Oct 1;56(4):873-883. doi: 10.7589/JWD-D-19-00008.
Before 2001, all serosurveys for morbilliviruses in sea otters (Enhydra lutris) in California, Washington, and Alaska, US, documented a 0% seroprevalence. The first published serologic detections of morbillivirus in sea otters occurred in 2001-02 in live-captured Washington sea otters, with a documented 80% seroprevalence. We conducted a retrospective study of sea otter cases from 1989 to 2010 compiled at the US Geological Survey, National Wildlife Health Center to identify cases of morbilliviral disease in Washington sea otters and to characterize the disease using immunohistochemistry, reverse transcription (RT)-PCR, genetic sequencing, virus isolation, and serology. We identified six cases of morbilliviral disease and 12 cases of morbilliviral infection in this population of sea otters during 2000-10. Significant histologic findings included inflammation in the white and gray matter of the brain characterized by lymphoplasmacytic perivascular cuffing, neuronal necrosis, and satellitosis in gray matter and by spongiosis, myelin degeneration, spheroids, and gemistocytes in white matter. Intranuclear and intracytoplasmic viral inclusion bodies were found in neurons, Purkinje cells, and glia. Immunohistochemistry for canine distemper virus (CDV) showed positive staining in neurons, glial cells, and cell processes. A pan-morbillivirus RT-PCR with subsequent restriction endonuclease digestion or sequencing identified CDV. Virus isolation was not successful. Two sea otters with morbilliviral encephalitis showed greater antibody titers to CDV than phocine distemper virus. Histologic changes were confined to the central nervous system and resembled neurologic canine distemper in domestic dogs. Cases of sea otters with morbilliviral infection without histologic changes could represent early infections or incompletely cleared sublethal infections. We found that morbillivirus was present in the Washington sea otter population as early as 2000, and we provide a description of the pathology of canine distemper in sea otters.
2001年之前，在美国加利福尼亚州、华盛顿州和阿拉斯加州对海獭（Enhydra lutris）进行的所有麻疹病毒血清学调查中，血清阳性率均记录为0%。首次发表的海獭麻疹病毒血清学检测结果于2001年至2002年出现在活体捕获的华盛顿海獭中，记录的血清阳性率为80%。我们对美国地质调查局国家野生动物健康中心汇编的1989年至2010年海獭病例进行了回顾性研究，以确定华盛顿海獭中麻疹病毒病的病例，并使用免疫组织化学、逆转录（RT）-PCR、基因测序、病毒分离和血清学对该病进行特征描述。我们在2000年至2010年期间的这群海獭中确定了6例麻疹病毒病病例和12例麻疹病毒感染病例。显著的组织学发现包括大脑白质和灰质的炎症，其特征为血管周围淋巴细胞浆细胞套袖样浸润、神经元坏死以及灰质中的卫星现象，白质中则表现为海绵状变性、髓鞘变性、球形体和肥胖细胞。在神经元、浦肯野细胞和神经胶质细胞中发现了核内和胞质内病毒包涵体。犬瘟热病毒（CDV）免疫组织化学显示在神经元、神经胶质细胞和细胞突起中呈阳性染色。一种通用麻疹病毒RT-PCR随后进行限制性内切酶消化或测序鉴定出了CDV。病毒分离未成功。两只患有麻疹病毒性脑炎的海獭对CDV的抗体滴度高于海豹瘟热病毒。组织学变化局限于中枢神经系统，类似于家犬的神经性犬瘟热。没有组织学变化的麻疹病毒感染海獭病例可能代表早期感染或未完全清除的亚致死性感染。我们发现麻疹病毒早在2000年就存在于华盛顿海獭种群中，并且我们提供了海獭犬瘟热病理学的描述。
