Engineering strategies for insect viruses and microbes for dsRNA production and delivery to insects for targeted gene silencing

Abstract

RNA interference (RNAi)-based pest control is viewed as a safe and effective method for insect pest control. However, the stability and efficient cellular delivery of the double stranded RNA (dsRNA) active molecule remains crucial to its success in pest control. Among the different approaches that have been proposed to improve dsRNA delivery in insects, the use of nano-carriers, engineered viruses and engineered microbes have been successfully employed in proofof-concept studies. This review focuses on engineering approaches that have been successfully employed to modify insect viruses and different microbes for dsRNA production and delivery in insects. First, the different viral vector systems based on insect RNA and DNA viruses for dsRNA delivery are discussed. Second, a comprehensive overview of different microbe-based (bacteria, fungi, microalgae) dsRNA production and delivery systems that have been developed till date are presented. Finally, future perspectives on the development of other delivery systems with potential in the context of insect pest control are provided. Overall, this review is expected to stimulate awareness, interest, insight and research into promising sources of biotechnologically interesting viruses and microbes for protecting agriculture and human health against insect pests.

Prospects for deploying microbes against tree-killing beetles (Coleoptera) in Anthropocene

“…Interestingly, using microbes (i.e., bacterial minicells) as dsRNA carriers and for mass production seems a promising alternative to pesticides (Guan et al, 2021;Whitten et al, 2023;Xue et al, 2023). Unfortunately, investigation on these vesicles for dsRNA delivery is limited; however, specific companies, e.g., AgroSpheres, 1 delve into such technology for dsRNA or siRNA delivery for agricultural field applications.…”

“…Unfortunately, investigation on these vesicles for dsRNA delivery is limited; however, specific companies, e.g., AgroSpheres, 1 delve into such technology for dsRNA or siRNA delivery for agricultural field applications. Another attractive option might be the co-expression of viral-like particles (VLPs) (Xue et al, 2023) and dsRNA inside the bacterial cell to use in the forest or isolate dsRNA-containing particles using the capacity of VLPs to self-assemble in vitro. Replicating engineered viruses permit superior cellular uptake and protection of the dsRNA in the extracellular environments in the forest (Kroemer et al, 2015;Sun, 2015;Xue et al, 2023), but after the COVID-19 pandemic, the approval of such alternatives might encounter hurdles to receive societal acceptance.…”

“…Alternatively, expressing dsRNA targeting specific pest insects inside recombinant bacteria or yeast lacking RNase III activity is a rewarding alternative when applied to the food source (Tian et al, 2009;Zhang et al, 2019;Ma et al, 2023). SMR is an advancement of this approach using symbiotic 1 https://www.agrospheres.com/ microbes as a carrier for the species-specific dsRNA delivery against target pests (Whitten et al, 2016;Xue et al, 2023). SMR has selective advantages over other strategies.…”

Towards dsRNA‐integrated protection of medical Cannabis crops: considering human safety, recent‐ and developing RNAi methods, and research inroads

“…Sensitivity to dsRNA has been shown to vary dramatically, both between and within taxonomic groups 79,80 . With regard to exogenously applied dsRNA, some major hurdles here may be mitigated through the use of nanocarriers, 81,82 engineered microbial carriers, 83 or the co‐targeting of specific molecules (e.g. dsRNases) 53 .…”