The Antiviral Small-Interfering RNA Pathway Induces Zika Virus Resistance in Transgenic Aedes aegypti.

Adeline E Williams,Alexander W.E Franz,Irma Sanchez-Vargas,Ken E Olson,Jingyi Lin,William R Reid

doi:10.3390/v12111231

Adeline E Williams, Alexander W.E Franz + Show 4 more

Open Access

https://doi.org/10.3390/v12111231

Copy DOI

Journal: Viruses	Publication Date: Oct 30, 2020
Citations: 20	License type: CC BY 4.0

Affiliation: Colorado State University, University of Missouri

Abstract

The resurgence of arbovirus outbreaks across the globe, including the recent Zika virus (ZIKV) epidemic in 2015–2016, emphasizes the need for innovative vector control methods. In this study, we investigated ZIKV susceptibility to transgenic Aedes aegypti engineered to target the virus by means of the antiviral small-interfering RNA (siRNA) pathway. The robustness of antiviral effector expression in transgenic mosquitoes is strongly influenced by the genomic insertion locus and transgene copy number; we therefore used CRISPR/Cas9 to re-target a previously characterized locus (Chr2:321382225) and engineered mosquitoes expressing an inverted repeat (IR) dsRNA against the NS3/4A region of the ZIKV genome. Small RNA analysis revealed that the IR effector triggered the mosquito’s siRNA antiviral pathway in bloodfed females. Nearly complete (90%) inhibition of ZIKV replication was found in vivo in both midguts and carcasses at 7 or 14 days post-infection (dpi). Furthermore, significantly fewer transgenic mosquitoes contained ZIKV in their salivary glands (p = 0.001), which led to a reduction in the number of ZIKV-containing saliva samples as measured by transmission assay. Our work shows that Ae. aegypti innate immunity can be co-opted to engineer mosquitoes resistant to ZIKV.

Highlights

Arthropod-borne viruses such as Zika (ZIKV; Flaviviridae; Flavivirus), dengue 1–4 (DENV1-4; Flaviviridae; Flavivirus), and chikungunya (CHIKV; Togaviridae; Alphavirus) are major public health burdens that continue to threaten hundreds of millions of people worldwide [1,2]
We previously found that synthetic resistance to arboviruses in Ae. aegypti could be achieved by co-opting the innate immune responses of the mosquito by utilizing its RNA interference (RNAi) pathway [19]
The inverted repeat (IR) sequence (Figure S1) was chosen based on previously published data that had identified the NS3/4A region of the viral genome to be highly conserved amongst different Zika virus (ZIKV) strains and a robust RNAi target [29]

Summary

Introduction

Arthropod-borne (arbo) viruses such as Zika (ZIKV; Flaviviridae; Flavivirus), dengue 1–4 (DENV1-4; Flaviviridae; Flavivirus), and chikungunya (CHIKV; Togaviridae; Alphavirus) are major public health burdens that continue to threaten hundreds of millions of people worldwide [1,2]. The main vector of these viruses is the urban dwelling, anthropophilic Aedes aegypti mosquito. Few to no vaccines or antiviral therapeutics are available for most arboviruses, including ZIKV, and limiting human exposure to infected mosquitoes remains the primary method for preventing disease transmission. Novel strategies to manage and prevent mosquito-borne diseases are desperately needed [4]. The generation of genetically modified mosquitoes to reduce disease burdens has been proposed as a vector control strategy that could complement currently implemented methods [5,6,7]. In 2016, for example, the WHO Zika virus research agenda (WHO reference number WHO/ZIKV/PHR/16.1)

Objectives

Methods

Results

Conclusion