黑守瓜中一种新negevirus的鉴定和分析

Identification and analysis of a novel negevirus isolated from a leaf beetle,Aulacophora lewisii

negevirus(nege-like virus)是病毒学领域新增的一个分类单元,主要包括在节肢动物中鉴定的一类昆虫特异性病毒。本研究利用宏转录组技术从黑守瓜(Aulacophora lewisii)中鉴定到一种新的negevirus,命名为Nbu Aulacophora lewisii nege-like virus 1(NbuALNV-1)。NbuALNV-1为正义单链RNA病毒,全基因组包含9 832个核苷酸(nucleotide, nt)(不包括多聚腺苷酸尾),5′、3′非翻译区长度分别为292、77 nt。NbuALNV-1基因组包含6个开放阅读框,预测具有5个典型的negeviruses保守结构域,包括病毒甲基转移酶结构域、RNA病毒解旋酶结构域、RNA依赖的RNA聚合酶(RNA-dependent RNA polymerase, RdRp)结构域、DISB-ORF2_chro结构域和SP24结构域。本研究利用NbuALNV-1和已报道的negeviruses的RdRp氨基酸序列基于最大似然法构建的系统发育分析表明,NbuALNV-1与Hubei Wuhan insect virus 9、Aphis glycines virus 3和Fort Crockett virus形成了一个独立分支,且该分支和北岛病毒科(Kitaviridae)的植物病毒在进化上具有相关性。此外,本研究对黑守瓜中NbuALNV-1病毒来源的干扰小RNA进行分析,发现这些干扰小RNA具有典型的病毒来源干扰小RNA的特征,表明NbuALNV-1能诱导宿主的RNA干扰抗病毒免疫反应。综上所述,本研究鉴定并分析了黑守瓜中的一种新的negevirus——NbuALNV-1,也是首次在鞘翅目昆虫中发现negevirus。

negevirus(nege-like virus) is a newly proposed virus taxon of insect-specific RNA viruses and has been found in various insect species. In this study, the complete genome of a novel nege-like virus, named as“Nbu Aulacophora lewisii nege-like virus 1”(NbuALNV-1), was identified from a single leaf beetle,Aulacophora lewisii. Nbu ALNV-1 is a positive-sense single-stranded RNA virus with the genome of 9 832nucleotide(nt) in length(excluding the poly A tail), with a 5′ untranslated region(UTR) of 292 nt and a 3′ UTR of77 nt, and six open reading frames(ORFs). Five conserved domains of negeviruses were predicted to be encoded by the genome of NbuALNV-1, consisting of the viral methyltransferase domain, RNA virus helicase domain,and RNA-dependent RNA polymerase(RdRp) domain in ORF1, and the DISB-ORF2_chro domain and SP24domain in the other two ORFs. Phylogenetic analysis of RdRp amino acid sequences of NbuALNV-1, together with Hubei Wuhan insect virus 9, Aphis glycines virus 3, and Fort Crockett virus showed that they formed as an“unclassified” clade and closely related to members in plant viruses of the family Kitaviridae. Furthermore,typical characteristics of virus-derived small interfering RNAs were observed by NbuALNV-1-derived small interfering RNAs, indicating that NbuALNV-1 might induce the host RNA interfering antiviral immune response. In summary, a nege-like virus was identified in A. lewisii, and NbuALNV-1 is the first negevirus discovered in the insect order Coleoptera.