An insect nidovirus emerging from a primary tropical rainforest.
An insect nidovirus emerging from a primary tropical rainforest.
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作者：
Zirkel F;Kurth A;Quan PL;Briese T;Ellerbrok H;Pauli G;Leendertz FH;Lipkin WI;Ziebuhr J;Drosten C;Junglen S
热带雨林显示出最高水平的陆地生物多样性，可能是微生物多样性的重要贡献者。对这些生态系统的开发利用可能会促进新型病原体的出现。我们报告了第一个昆虫相关的尼多病毒的发现，暂定名为Cavally病毒（CAVV）。在Côte科特迪瓦沿着人为干扰梯度对蚊子相关病毒进行调查时，发现CAVV的流行率为9.3%。生境特异性病毒多样性分析和祖先状态重建表明，CAVV起源于原始雨林，随后传播到农业和人类住区。病毒从森林向外扩展与病毒多样性降低（P < 0.01）和病毒流行率升高（P < 0.00001）相关。CAVV是一种包膜病毒，具有大的表面突起。RNA基因组由20108个核苷酸组成，具有7个主要的开放阅读框（orf）。ORF1a和-1b编码的两个大蛋白与Nidovirales的系统发育高级代表（包括Coronavirinae科和Torovirinae科）以及具有基础系统发育关系的科（包括Roniviridae和Arteriviridae）具有相同的基本特征。核糖核酸内切酶和解旋酶相关的锌结合结构域等遗传标记在腺病毒中是保守的。ORF2a和-2b分别编码结构蛋白S和N，而ORF3a和-3b编码跨膜区蛋白。CAVV产生三种亚基因组mrna，它们具有来自基因组5 ‘端的5 ’先导序列（不同长度）。这一新的与蚊子相关的尼多病毒群很可能代表了尼多病毒目中的一个新科。关于热带雨林中微生物多样性的知识很少，而驱动新型病原体出现的因素也知之甚少。我们发现并绘制了一种新型蚊子尼型病毒从原始雨林到人类住区的传播和遗传进化图谱。值得注意的是，在向受干扰生境扩散的过程中，病毒多样性下降，流行率上升。这种新型病毒，暂时被命名为Cavally病毒，具有与尼多病毒目（冠状病毒科、动脉病毒科和轮状病毒科）成员共同的遗传特征，包括复制酶机制的保存和亚基因组RNA信息的表达，与冠状病毒科具有基本的系统发育关系，与已建立的尼多病毒科明显不同。将这一假定的新家族纳入尼囊病毒系统发育中，表明尼囊病毒可能是从节肢动物进化而来的。
Tropical rainforests show the highest level of terrestrial biodiversity and may be an important contributor to microbial diversity. Exploitation of these ecosystems may foster the emergence of novel pathogens. We report the discovery of the first insect-associated nidovirus, tentatively named Cavally virus (CAVV). CAVV was found with a prevalence of 9.3% during a survey of mosquito-associated viruses along an anthropogenic disturbance gradient in Côte d’Ivoire. Analysis of habitat-specific virus diversity and ancestral state reconstruction demonstrated an origin of CAVV in a pristine rainforest with subsequent spread into agriculture and human settlements. Virus extension from the forest was associated with a decrease in virus diversity (P < 0.01) and an increase in virus prevalence (P < 0.00001). CAVV is an enveloped virus with large surface projections. The RNA genome comprises 20,108 nucleotides with seven major open reading frames (ORFs). ORF1a and -1b encode two large proteins that share essential features with phylogenetically higher representatives of the order Nidovirales, including the families Coronavirinae and Torovirinae, but also with families in a basal phylogenetic relationship, including the families Roniviridae and Arteriviridae. Genetic markers uniquely conserved in nidoviruses, such as an endoribonuclease- and helicase-associated zinc-binding domain, are conserved in CAVV. ORF2a and -2b are predicted to code for structural proteins S and N, respectively, while ORF3a and -3b encode proteins with membrane-spanning regions. CAVV produces three subgenomic mRNAs with 5′ leader sequences (of different lengths) derived from the 5′ end of the genome. This novel cluster of mosquito-associated nidoviruses is likely to represent a novel family within the order Nidovirales. Knowledge of microbial diversity in tropical rainforests is sparse, and factors driving the emergence of novel pathogens are poorly understood. We discovered and mapped the spread and genetic evolution of a novel mosquito nidovirus from a pristine rainforest to human settlements. Notably, virus diversity decreased and prevalence increased during the process of spreading into disturbed habitats. The novel virus, tentatively termed Cavally virus, contains genetic features common to members of the order Nidovirales (families Coronaviridae, Arteriviridae, and Roniviridae), including conservation of the replicase machinery and expression of subgenomic RNA messages, has a basal phylogenetic relationship to the family Coronaviridae, and clearly differs from the established nidovirus families. Inclusion of this putative novel family in the nidovirus phylogeny suggests that nidoviruses may have evolved from arthropods.