Viral Delivery of dsRNA for Control of Insect Agricultural Pests and Vectors of Human Disease: Prospects and Challenges

Abstract

RNAi is applied as a new and safe method for pest control in agriculture but efficiency and specificity of delivery of dsRNA trigger remains a critical issue. Various agents have been proposed to augment dsRNA delivery, such as engineered micro-organisms and synthetic nanoparticles, but the use of viruses has received relatively little attention. Here we present a critical view of the potential of the use of recombinant viruses for efficient and specific delivery of dsRNA. First of all, it requires the availability of plasmid-based reverse genetics systems for virus production, of which an overview is presented. For RNA viruses, their application seems to be straightforward since dsRNA is produced as an intermediate molecule during viral replication, but DNA viruses also have potential through the production of RNA hairpins after transcription. However, application of recombinant virus for dsRNA delivery may not be straightforward in many cases, since viruses can encode RNAi suppressors, and virus-induced silencing effects can be determined by the properties of the encoded RNAi suppressor. An alternative is virus-like particles that retain the efficiency and specificity determinants of natural virions but have encapsidated non-replicating RNA. Finally, the use of viruses raises important safety issues which need to be addressed before application can proceed.

RNA interference technology in crop protection against arthropod pests, pathogens and nematodes

“…In VIGS, a pest‐specific RNAi inducer sequence is introduced into a non‐pathogenic engineered virus; following exposure of the engineered virus to the pest cells, siRNAs specific for the target gene mRNAs in the pest will be silenced . VIGS in an insect or pathogen can be induced when it feeds on a plant infected with the engineered virus . The plant virus TRV, expressing the antisense fragments for a dsRNA specific to a chewing insect, Manduca sexta , in Nicotiana attenuata plants, was reported to specifically silence three midgut‐expressed MsCYP RNAs when the larvae were fed on these plants.…”

“…17,77 VIGS in an insect or pathogen can be induced when it feeds on a plant infected with the engineered virus. 18,78,79 The plant virus TRV, expressing the antisense fragments for a dsRNA specific to a chewing insect, Manduca sexta, in Nicotiana attenuata plants, was reported to specifically silence three midgut-expressed MsCYP RNAs when the larvae were fed on these plants. In addition to the use of plant viruses as insect-specific dsRNA delivery vectors, another potential VIGS approach is the use of recombinant viruses, which can infect and replicate in the host insect.…”

A novel cypovirus found in a betabaculovirus co-infection context contains a poxvirus immune nuclease (poxin)-related gene

“…Insect hosts are frequently infected simultaneously by many virus members of the same or distinct viral families [34,35]. However, few studies on the association of baculoviruses and cypoviruses during infection of the same insect have been carried out.…”

BAPC-assistedCRISPR/Cas9 System: Targeted Delivery into Adult Ovaries for Heritable Germline Gene Editing (Arthropoda: Hemiptera)

“…Advances in biotechnologies, like CRISPR and RNAi provides new sustainable and environmentally friendly strategies to reduce insect vectors, like psyllids (Andrade & Hunter 2016; 2017; Hunter & Sinisterra-Hunter 2018; Taning et al, 2016; Ghosh et al, 2018). These advances will also aid in the management of many other insect vectors and pests (Chaverra-Rodriguez et al, 2018; Darrington et al, 2017; Dong, et al, 2015; 2018; Gantz & Akbari 2018; Ghosh et al, 2018; Kolliopoulou et al, 2017; Sinisterra-Hunter & Hunter 2018; Taning et al, 2017; Zotti et al, 2018).…”

“…These techniques include targeted RNA suppression, gene regulation, and gene editing in all organisms: bacteria, plants, animals, and humans. As traditional chemical insecticides fail to provide adequate pest management, due to development of chemical resistance, dependence upon biotech strategies for management have become the best options for development of therapeutic treatments to reduce arthropod vectors, the pathogens, or to cause disruption of vector pathogen acquisition and transmission (Andrade & Hunter 2016; Baum & Roberts 2014; Gantz & Akbari 2018; Hunter & Sinisterra-Hunter 2018; Kolliopoulou et al, 2017; Roberts et al, 2015; Petrick et al, 2013;2016; Scott et al, 2013; Sinisterra-Hunter & Hunter 2018; Taning et al, 2017; Zotti et al, 2018). The rapid emergence of gene editing techniques, like CRISPR/Cas9, Clustered regularly interspaced short palindromic repeats (CRISPR) and the CRISPR-associated protein, Cas9, provide precise editing of genes across all species (Doudna & Charpentier 2014; Peng et al, 2014; Wang et al 2016).…”