Delivery of Lethal dsRNAs in Insect Diets by Branched Amphiphilic Peptide Capsules

Abstract

Branched Amphiphilic Peptides Capsules (BAPCs™) are a novel class of nano‐carriers constituted from the spontaneous co‐assembly of two unique, engineered peptide sequences. We recently reported on a thermally induced variant of BAPC™ that demonstrates promise as a vehicle for nucleic acid delivery and transcript knockdown. These BAPCs™ display a uniform size of 20–30 nm; they are easy to synthesize, stable and produce minimal immunogenic and inflammatory responses, in contrast to those commonly observed with viral and cationic lipid based approaches for gene delivery. BAPCs™ act as cationic nucleation centers allowing nucleic to wrap around them in a nucleosome like fashion, generating peptide‐nucleic complexes with sizes ranging from 80 to 200 nm. In this study, development of new and specific insect pest management methods capable of overcoming pesticide resistance and collateral off‐target killings are described. Gene silencing by feeding dsRNA to insects shows promise in this area. Here Branched Amphiphilic Peptide Capsules (BAPCs), facilitate cellular uptake of dsRNA by insects through feeding. The insect diets included dsRNA (300–400 bps) with and without complexation with BAPCs. The selected insect species come from two different Orders with different feeding mechanisms: Tribolium castaneum and Acyrthosiphon pisum. The gene transcripts tested (BiP and Armet) are part of the unfolded protein response (UPR) and suppressing their translation resulted in lethality. For Acyrthosiphon pisum, ingestion of BiP‐dsRNA associated with BAPCs led to the premature death of the aphids (t1/2 = 4–5 days) compared to ingestion of the same amounts of free BiP‐dsRNA (t1/2 = 11–12 days). Tribolium castaneum was effectively killed using a combination of BiP‐dsRNA and Armet‐dsRNA complexed with BAPCs; most dying as larvae or during eclosion (~75%). Feeding dsRNA alone resulted in fewer deaths (~30%). The results show that complexation of dsRNA with BAPCs enhanced the oral delivery of dsRNA over dsRNA alone.Support or Funding InformationPartial support for this project was provided by the Terry Johnson Cancer Center at Kansas State University and by the USDA's National Institute of Food and Agriculture through the Specialty Crops Research Initiative/Citrus Disease Research & Extension, USDA NIFA Award No. 2015‐70016‐23028 and an Institutional Development Award (IDeA) from NIGMS grant P20 GM103418.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Advances in nanocarriers to improve the stability of dsRNA in the environment

“…Shen jie’s team conducted research on the mechanism and delivery process of RNAi mediated by nanoparticles and proposed that the efficient protection and delivery of dsRNA by nanocarriers was the key factor that enhanced the efficiency of RNAi ( Ma et al, 2022 ). The formulation of nanocarriers with dsRNA to build a stable and efficient dsRNA delivery system produced a solution for the stable existence of dsRNA in the environment ( Barros et al, 2019 ; Linyu et al, 2021 ) ( Figure 1 ). Nanocarriers has several significant advantages.…”

“…The amphiphilic polypeptide capsules can promote the uptake of dsRNA by cells of the Tribolium castaneum and Acyrthosiphon pisum , and increase the mortality rate. Amphiphilic peptide capsules are similar to guanidine polymer nanoparticles in that they can also remain highly stable in strong alkaline environments ( Barros et al, 2019 ). This nanocarrier is highly biocompatible and has strong abilities to target and penetrate cells, but its high production cost limits its marketability.…”