Culley Alexander I, Lang Andrew S, Suttle Curtis A
Department of Botany, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.
Nature. 2003 Aug 28;424(6952):1054-7. doi: 10.1038/nature01886.
Picorna-like viruses are a loosely defined group of positive-sense single-stranded RNA viruses that are major pathogens of animals, plants and insects. They include viruses that are of enormous economic and public-health concern and are responsible for animal diseases (such as poliomyelitis), plant diseases (such as sharka) and insect diseases (such as sacbrood). Viruses from the six divergent families (the Picornaviridae, Caliciviridae, Comoviridae, Sequiviridae, Dicistroviridae and Potyviridae) that comprise the picorna-like virus superfamily have the following features in common: a genome with a protein attached to the 5' end and no overlapping open reading frames, all the RNAs are translated into a polyprotein before processing, and a conserved RNA-dependent RNA polymerase (RdRp) protein. Analyses of RdRp sequences from these viruses produce phylogenies that are congruent with established picorna-like virus family assignments; hence, this gene is an excellent molecular marker for examining the diversity of picorna-like viruses in nature. Here we report, on the basis of analysis of RdRp sequences amplified from marine virus communities, that a diverse array of picorna-like viruses exists in the ocean. All of the sequences amplified were divergent from known picorna-like viruses, and fell within four monophyletic groups that probably belong to at least two new families. Moreover, we show that an isolate belonging to one of these groups is a lytic pathogen of Heterosigma akashiwo, a toxic-bloom-forming alga responsible for severe economic losses to the finfish aquaculture industry, suggesting that picorna-like viruses are important pathogens of marine phytoplankton.
类微小核糖核酸病毒是一类定义较为宽泛的正义单链RNA病毒，是动物、植物和昆虫的主要病原体。它们包括一些引起巨大经济和公共卫生问题的病毒，可导致动物疾病（如脊髓灰质炎）、植物疾病（如苹果褪绿叶斑病）和昆虫疾病（如蜜蜂囊状幼虫病）。构成类微小核糖核酸病毒超家族的六个不同科（微小核糖核酸病毒科、杯状病毒科、豇豆花叶病毒科、伴生病毒科、双顺反子病毒科和马铃薯Y病毒科）的病毒具有以下共同特征：基因组5'端附着有蛋白质且无重叠开放阅读框，所有RNA在加工前先翻译成多聚蛋白，以及一种保守的RNA依赖性RNA聚合酶（RdRp）蛋白。对这些病毒的RdRp序列进行分析可得出与已确定的类微小核糖核酸病毒科分类一致的系统发育树；因此，该基因是检测自然界中类微小核糖核酸病毒多样性的优良分子标记。在此，我们基于对从海洋病毒群落中扩增的RdRp序列的分析报告称，海洋中存在各种各样的类微小核糖核酸病毒。所有扩增得到的序列均与已知的类微小核糖核酸病毒不同，且属于四个单系类群，可能至少分属于两个新科。此外，我们表明属于这些类群之一的一个分离株是赤潮异弯藻的裂解性病原体，赤潮异弯藻是一种形成有毒藻华的藻类，给鱼类养殖业造成严重经济损失，这表明类微小核糖核酸病毒是海洋浮游植物的重要病原体。
