Sydney Institute for Infectious Diseases, School of Medical Sciences, The University of Sydney, Sydney, NSW 2006, Australia.
Department of Microbiology and Immunology, University of Otago, Dunedin 9016, New Zealand.
Viruses. 2022 Oct 4;14(10):2186. doi: 10.3390/v14102186.
nodavirus (MrNV)-the aetiological agent of white tail disease-is a major limiting factor of crustacean aquaculture as it causes up to 100% mortality in larvae and juveniles. Despite the importance of MrNV, there have been few studies on the phylogenetic diversity and geographic range of this virus in Australian waterways. Here, we detected MrNV genomes in common carp () metatranscriptomes sampled at five freshwater sites across the Murray-Darling Basin (MDB), Australia. We identified genetic divergence of the RNA-dependent RNA polymerase gene between MrNV sequences identified in the northern and southern rivers of the MDB. Northern viruses exhibited strong phylogenetic clustering with MrNV from China, whereas the southern viruses were more closely related to MrNV from Australia. However, all five viruses were closely related in the capsid protein, indicative of genetic reassortment of the RNA1 and RNA2 segments between Australian and introduced MrNV. In addition, we identified in two of the five MrNV-positive libraries, suggesting that these species may be important reservoir hosts in the MDB. Overall, this study reports the first occurrence of MrNV outside of the Queensland region in Australia and provides evidence for genetic reassortment between endemic and introduced MrNV.
诺达病毒（MrNV）是一种引发虾夷扇贝白便病的病原体，它是水产养殖的主要限制因素，因为它会导致幼虫和幼体 100%死亡。尽管 MrNV 非常重要，但对澳大利亚水域中这种病毒的系统发育多样性和地理范围的研究却很少。在这里，我们从澳大利亚墨累-达令盆地（MDB）五个淡水地点采集的鲤鱼宏转录组中检测到了 MrNV 基因组。我们发现 MDB 北部和南部河流中 MrNV 的 RNA 依赖性 RNA 聚合酶基因存在遗传差异。北部病毒与来自中国的 MrNV 表现出强烈的系统发育聚类，而南部病毒与来自澳大利亚的 MrNV 更为密切相关。然而，所有五个病毒在衣壳蛋白上都非常密切相关，表明澳大利亚和引入的 MrNV 之间的 RNA1 和 RNA2 片段发生了遗传重配。此外，我们在五个 MrNV 阳性文库中的两个文库中鉴定到了 ，这表明这些物种可能是 MDB 中的重要储存宿主。总的来说，本研究报告了 MrNV 在澳大利亚昆士兰州以外的首次出现，并提供了有关地方性和引入性 MrNV 之间遗传重配的证据。
