Clouthier Sharon C, Vanwalleghem Elissa, Copeland Shelagh, Klassen Cheryl, Hobbs Gary, Nielsen Ole, Anderson Eric D
Freshwater Institute, Fisheries & Oceans Canada, Winnipeg, Manitoba, Canada.
Dis Aquat Organ. 2013 Feb 28;102(3):195-209. doi: 10.3354/dao02548.
A newly discovered virus, Namao virus, associated with morbidity and mortality, was detected among juvenile lake sturgeon Acipenser fulvescens being propagated by a conservation stocking program for this endangered species in Manitoba, Canada. The outbreaks resulted in cumulative mortalities of 62 to 99.6% among progeny of wild Winnipeg River or Nelson River lake sturgeon and occurred at 2 geographically separate facilities. Namao virus was detected in almost 94% of the moribund or dead lake sturgeon according to a conventional polymerase chain reaction (cPCR) test that is based upon amplification of a 219 bp fragment of the virus major capsid protein (MCP). The virus itself was large (242 to 282 nm) and icosahedral-shaped with 2 capsids and a condensed bar-shaped core. It was found in virus factories within the host cell cytoplasm and displayed a tropism for the integument. Namao virus caused cellular changes characterized by enlarged eosinophilic epithelial cells in the gills and skin. Samples suspected of containing Namao virus did not have cytopathic effects on primary lake sturgeon or established white sturgeon cell lines. However, viral nucleic acid was detected in the former after prolonged incubation periods. Using primers designed from conserved regions of the MCP from NCLDVs, an estimated 95 to 96% of the Namao virus MCP open reading frame was captured. Phylogenetic analysis using the MCP of Namao virus and 27 other NCLDVs suggested that Namao virus and white sturgeon iridovirus share a common evolutionary past and might be members of the family Mimiviridae or a new, as yet unrecognized, virus family.
在加拿大曼尼托巴省一项针对濒危物种湖鲟（Acipenser fulvescens）的保护性放流计划所繁育的幼体湖鲟中，检测到一种新发现的与发病和死亡相关的病毒——纳毛病毒。疫情导致野生温尼伯河或尼尔森河湖鲟后代的累计死亡率达62%至99.6%，且疫情发生在两个地理位置相隔的设施中。根据基于病毒主要衣壳蛋白（MCP）219 bp片段扩增的常规聚合酶链反应（cPCR）检测，在近94%濒死或死亡的湖鲟中检测到了纳毛病毒。该病毒本身较大（242至282纳米），呈二十面体形状，有2个衣壳和一个浓缩的棒状核心。它存在于宿主细胞质内的病毒工厂中，对体表有嗜性。纳毛病毒引起细胞变化，其特征为鳃和皮肤中嗜酸性上皮细胞肿大。疑似含有纳毛病毒的样本对原代湖鲟或已建立的白鲟细胞系没有细胞病变效应。然而，经过较长潜伏期后，在前一种样本中检测到了病毒核酸。使用从核质大DNA病毒（NCLDVs）的MCP保守区域设计的引物，捕获了约95%至96%的纳毛病毒MCP开放阅读框。使用纳毛病毒的MCP和其他27种NCLDVs进行的系统发育分析表明，纳毛病毒和白鲟虹彩病毒有共同的进化史，可能是 Mimiviridae 科或一个新的、尚未被认可的病毒科的成员。
