Genetically Modifying the Insect Gut Microbiota to Control Chagas Disease Vectors through Systemic RNAi

Abstract

Technologies based on RNA interference may be used for insect control. Sustainable strategies are needed to control vectors of Chagas disease such as Rhodnius prolixus. The insect microbiota can be modified to deliver molecules to the gut. Here, Escherichia coli HT115(DE3) expressing dsRNA for the Rhodnius heme-binding protein (RHBP) and for catalase (CAT) were fed to nymphs and adult triatomine stages. RHBP is an egg protein and CAT is an antioxidant enzyme expressed in all tissues by all developmental stages. The RNA interference effect was systemic and temporal. Concentrations of E. coli HT115(DE3) above 3.35 × 107 CFU/mL produced a significant RHBP and CAT gene knockdown in nymphs and adults. RHBP expression in the fat body was reduced by 99% three days after feeding, returning to normal levels 10 days after feeding. CAT expression was reduced by 99% and 96% in the ovary and the posterior midgut, respectively, five days after ingestion. Mortality rates increased by 24-30% in first instars fed RHBP and CAT bacteria. Molting rates were reduced by 100% in first instars and 80% in third instars fed bacteria producing RHBP or CAT dsRNA. Oviposition was reduced by 43% (RHBP) and 84% (CAT). Embryogenesis was arrested in 16% (RHBP) and 20% (CAT) of laid eggs. Feeding females 105 CFU/mL of the natural symbiont, Rhodococcus rhodnii, transformed to express RHBP-specific hairpin RNA reduced RHBP expression by 89% and reduced oviposition. Modifying the insect microbiota to induce systemic RNAi in R. prolixus may result in a paratransgenic strategy for sustainable vector control.

Triatomine bugs, their microbiota and Trypanosoma cruzi: asymmetric responses of bacteria to an infected blood meal

“…It has been suggested that transmission might be controlled through the vector microbiota, since some strains of Serratia marcescens , a common symbiont of various triatomine species, have trypanolytic activity on several T. cruzi strains [12]. Methods for genetically modifying bacterial symbionts to effectively decrease parasite transmission or the development and fecundity of triatomine bugs have been established [13, 14]. …”

Plant Virus–Insect Vector Interactions: Current and Potential Future Research Directions

“…Recently, bacteria have been utilized as a vehicle to generate and deliver double-stranded RNA (dsRNA) to mosquitoes to manipulate gene expression, and adaptation of this approach to manipulate arbovirus infection is an interesting (but yet unrealized) para-transgenic approach [157,158]. Other para-transgenic approaches could be developed using the diverse microbiota of the mosquito, although to date these approaches have focused mainly on control of malarial parasites.…”

The microbiome modulates arbovirus transmission in mosquitoes

“…In addition to bacteria, fungi and viruses are also promising candidates for use in paratransgenic control [61,62]. Excitingly, bacteria have been used to generate and transfer dsRNA to manipulate mosquito gene expression, offering new prospects for paratransgenesis strategies to reduce arboviruses [63 • ,64 • ]. The ability to deliver RNAi into field mosquito populations would be highly desirable and enable the development of a myriad of control approaches.…”