Department of Pathology, Microbiology, and Immunology, University of California-Davis School of Veterinary Medicine, Davis, California, United States of America.
Vitalant Research Institute, San Francisco, California, United States of America.
PLoS One. 2020 Dec 17;15(12):e0244056. doi: 10.1371/journal.pone.0244056. eCollection 2020.
Viral infections were investigated in American black bears (Ursus americanus) from Nevada and northern California with and without idiopathic encephalitis. Metagenomics analyses of tissue pools revealed novel viruses in the genera Circoviridae, Parvoviridae, Anelloviridae, Polyomaviridae, and Papillomaviridae. The circovirus and parvovirus were of particular interest due to their potential importance as pathogens. We characterized the genomes of these viruses and subsequently screened bears by PCR to determine their prevalence. The circovirus (Ursus americanus circovirus, UaCV) was detected at a high prevalence (10/16, 67%), and the chaphamaparvovirus (Ursus americanus parvovirus, UaPV) was found in a single bear. We showed that UaCV is present in liver, spleen/lymph node, and brain tissue of selected cases by in situ hybridization (ISH) and PCR. Infections were detected in cases of idiopathic encephalitis and in cases without inflammatory brain lesions. Infection status was not clearly correlated with disease, and the significance of these infections remains unclear. Given the known pathogenicity of a closely related mammalian circovirus, and the complex manifestations of circovirus-associated diseases, we suggest that UaCV warrants further study as a possible cause or contributor to disease in American black bears.
对美国黑熊（Ursus americanus）进行了病毒感染研究，这些黑熊来自内华达州和北加利福尼亚州，分为有无特发性脑炎两种情况。对组织池的宏基因组分析揭示了圆环病毒科、细小病毒科、圆环病毒科、多瘤病毒科和乳头瘤病毒科的新病毒。由于circovirus 和 parvovirus 作为病原体的潜在重要性，因此特别引起了关注。我们对这些病毒的基因组进行了特征描述，随后通过 PCR 对黑熊进行了筛查，以确定其流行率。circovirus（美国黑熊圆环病毒，UaCV）的检出率很高（16 只中有 10 只，67%），而 chaphamaparvovirus（美国黑熊细小病毒，UaPV）仅在一只熊中发现。我们通过原位杂交（ISH）和 PCR 显示 UaCV 存在于选定病例的肝脏、脾脏/淋巴结和脑组织中。在特发性脑炎病例和无炎症性脑损伤病例中均检测到感染。感染状态与疾病无明显相关性，这些感染的意义尚不清楚。鉴于密切相关的哺乳动物 circovirus 的已知致病性，以及 circovirus 相关疾病的复杂表现，我们建议将 UaCV 作为可能的病因或导致美国黑熊疾病的因素进一步研究。
