Complete genome sequence of a novel nege-like virus in aphids (genus Indomegoura)

Leveraging insect viruses and genetic manipulation for sustainable agricultural pest control

The potential of insect viruses in the biological control of agricultural pests is well-recognized, yet their practical application faces obstacles such as host specificity, variable virulence, and resource scarcity. High-throughput sequencing (HTS) technologies have significantly advanced our capabilities in discovering and identifying new insect viruses, thereby enriching the arsenal for pest management. Concurrently, progress in reverse genetics has facilitated the development of versatile viral expression vectors. These vectors have enhanced the specificity and effectiveness of insect viruses in targeting specific pests, offering a more precise approach to pest control. This review provides a comprehensive examination of the methodologies employed in the identification of insect viruses using HTS. Additionally, it explores the domain of genetically modified insect viruses and their associated challenges in pest management. The adoption of these cutting-edge approaches holds great promise for developing environmentally sustainable and effective pest control solutions. © 2023 Society of Chemical Industry.

Identification and Genome Characterization of a Novel Nege-like Virus Isolated from Aphids (Aphis gossypii) in Yunnan Province

Negeviruses are insect-specific enveloped RNA viruses that exhibit a wide geographic distribution. A novel nege-like virus, tentatively named Aphis gossypii nege-like virus (AGNLV, GenBank: OR880429.1), was isolated from aphids (Aphis gossypii) in Lijiang City, Yunnan, China. AGNLV has a genome sequence of 9258 nt (excluding the polyA tail) encoding three open reading frames (ORFs). ORF1 (7149 nt) encodes a viral methyltransferase, a viral RNA helicase, and an RNA-dependent RNA polymerase. ORF2 (1422 nt) encodes a DiSB-ORF2_chro domain and ORF3 encodes an SP24 domain. The genome sequence of AGNLV shares the highest nucleotide identity of 60.0% and 59.5% with Wuhan house centipede virus 1 (WHCV1) and Astegopteryx formosana nege-like virus (AFNLV), respectively. Phylogenetic analysis based on the RNA-dependent RNA polymerase shows that AGNLV is clustered with other negeviruses and nege-like viruses discovered in aphids, forming a distinct "unclassified clade". Interestingly, AGNLV only encodes three ORFs, whereas AFNLV and WHCV1 have four ORFs. Structure and transmembrane domain predictions show the presence of eight alpha helices and five transmembrane helices in the AGNLV ORF3. Translational enhancement of the AGNLV 5' UTR was similar to that of the 5' UTR of plant viruses. Our findings provide evidence of the diversity and structure of nege-like viruses and are the first record of such a virus from a member of the genus Aphis.

Analysis of a new negevirus-like sequence from Bemisia tabaci unveils a potential new taxon linking nelorpi- and centiviruses

This study presents the complete genome sequence of a novel nege-like virus identified in whiteflies (Bemisia tabaci MEAM1), provisionally designated as whitefly negevirus 1 (WfNgV1). The virus possesses a single-stranded RNA genome comprising 11,848 nucleotides, organized into four open reading frames (ORFs). These ORFs encode the putative RNA-dependent-RNA-polymerase (RdRp, ORF 1), a glycoprotein (ORF 2), a structural protein with homology to those in the SP24 family, (ORF 3), and a protein of unknown function (ORF 4). Phylogenetic analysis focusing on RdRp and SP24 amino acid sequences revealed a close relationship between WfNgV1 and Bemisia tabaci negevirus 1, a negevirus sequence recently discovered in whiteflies from Israel. Both viruses form a clade sharing a most recent common ancestor with the proposed nelorpivirus and centivirus taxa. The putative glycoprotein from ORF 2 and SP24 (ORF 3) of WfNgV1 exhibit the characteristic topologies previously reported for negevirus counterparts. This marks the first reported negevirus-like sequence from whiteflies in the Americas.

Complete genome analysis of a nege-like virus in aphids (Astegopteryx formosana)

Negeviruses are a group of insect-specific viruses that have a wide geographic distribution and broad host range. In recent years, nege-like viruses have been discovered in aphids of various genera of the family Aphididae, including Aphis, Rhopalosiphum, Sitobion, and Indomegoura. Here, we report the complete genome sequence of a nege-like virus isolated from Astegopteryx formosana aphids collected in Guangdong, China, which we have designated as "Astegopteryx formosana nege-like virus" (AFNLV). AFNLV has a genome length of 10,107 nt (excluding the polyA tail) and possesses the typical conserved domains of negeviruses. These include a viral methyltransferase, an S-adenosylmethionine-dependent methyltransferase, a viral helicase, and an RNA-dependent RNA polymerase (RdRP) domain in open reading frame 1 (ORF1), a DiSB-ORF2_chro domain in ORF2, and a SP24 domain in ORF3. The genome of AFNLV shares the highest nucleotide sequence identity (74.89%) with Wuhan house centipede virus, identified in a mixture of barley aphids. As clearly revealed by RdRP-based phylogenetic analysis, AFNLV, together with other negeviruses and nege-like viruses discovered in aphids, formed a distinct "unclassified clade" closely related to members of the proposed genus "Sandewavirus" and the family Kitaviridae. In addition, small interfering RNAs (siRNAs) derived from AFNLV did not exhibit typical characteristics of virus-derived siRNAs processed by the host RNAi-based antiviral pathway. However, the extremely high abundance of viral transcripts (average read coverage 73,403X) strongly suggested that AFNLV might actively replicate in the aphid host. AFNLV described in this study is the first nege-like virus discovered in aphids of the genus Astegopteryx, which will contribute to future study of the co-evolution of nege/nege-like viruses and their host aphids.