Mosquito-borne diseases are a major threat to human health and are responsible for millions of deaths globally each year. Vector control is one of the most important approaches used in reducing the incidence of these diseases. However, increasing mosquito resistance to chemical insecticides presents challenges to this approach. Therefore, new strategies are necessary to develop the next generation vector control methods. Because of the target specificity of dsRNA, RNAi-based control measures are an attractive alternative to current insecticides used to control disease vectors. In this study, Chitosan (CS) was cross-linked to sodium tripolyphosphate (TPP) to produce nano-sized polyelectrolyte complexes with dsRNA. CS-TPP-dsRNA nanoparticles were prepared by ionic gelation method. The encapsulation efficiency, protection of dsRNA from nucleases, cellular uptake, in vivo biodistribution, larval mortality and gene knockdown efficiency of CS-TPP-dsRNA nanoparticles were determined. The results showed that at a 5:1 weight ratio of CS-TPP to dsRNA, nanoparticles of less than 200 nm mean diameter and a positive surface charge were formed. Confocal microscopy revealed the distribution of the fed CS-TPP-dsRNA nanoparticles in midgut, fat body and epidermis of yellow fever mosquito, Aedes aegypti larvae. Bioassays showed significant mortality of larvae fed on CS-TPP-dsRNA nanoparticles. These assays also showed knockdown of a target gene in CS-TPP-dsRNA nanoparticle fed larvae. These data suggest that CS-TPP nanoparticles may be used for delivery of dsRNA to mosquito larvae.
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Research is supported by grants from the National Institutes of Health (GM070559-12 and 1R21AI131427-01) and the National Institute of Food and Agriculture, US Department of Agriculture (under HATCH Project 2351177000).
Supplementary information accompanies this paper at https://doi.org/10.1038/s41598-019-45019-z.
Dhandapani, Ramesh Kumar; Gurusamy, Dhandapani; Howell, Jeffrey L.; and Palli, Subba Reddy, "Development of CS-TPP-dsRNA Nanoparticles to Enhance RNAi Efficiency in the Yellow Fever Mosquito, Aedes aegypti" (2019). Entomology Faculty Publications. 188.