RNAi gene knockdown in the poultry red mite, Dermanyssus gallinae (De Geer 1778), a tool for functional genomics

Wan Chen,Francesca Nunn,Alasdair J Nisbet,Kathryn Bartley,Alan S Bowman,Jeremy M Sternberg,Daniel R G Price,Stewart T G Burgess

doi:10.1186/s13071-020-04562-9

Wan Chen, Francesca Nunn + Show 6 more

Open Access

https://doi.org/10.1186/s13071-020-04562-9

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Abstract

BackgroundThe avian haematophagous ectoparasite Dermanyssus gallinae, commonly known as the poultry red mite, causes significant economic losses to the egg-laying industry worldwide and also represents a significant welfare threat. Current acaricide-based controls are unsustainable due to the mite’s ability to rapidly develop resistance, thus developing a novel sustainable means of control for D. gallinae is a priority. RNA interference (RNAi)-mediated gene silencing is a valuable tool for studying gene function in non-model organisms, but is also emerging as a novel tool for parasite control.MethodsHere we use an in silico approach to identify core RNAi pathway genes in the recently sequenced D. gallinae genome. In addition we utilise an in vitro feeding device to deliver double-stranded (ds) RNA to D. gallinae targeting the D. gallinae vATPase subunit A (Dg vATPase A) gene and monitor gene knockdown using quantitative PCR (qPCR).ResultsCore components of the small interfering RNA (siRNA) and microRNA (miRNA) pathways were identified in D. gallinae, which indicates that these gene silencing pathways are likely functional. Strikingly, the P-element-induced wimpy testis (PIWI)-interacting RNA (piRNA) pathway was absent in D. gallinae. In addition, feeding Dg vATPase A dsRNA to adult female D. gallinae resulted in silencing of the targeted gene compared to control mites fed non-specific lacZ dsRNA. In D. gallinae, dsRNA-mediated gene knockdown was rapid, being detectable 24 h after oral delivery of the dsRNA, and persisted for at least 120 h.ConclusionsThis study shows the presence of core RNAi machinery components in the D. gallinae genome. In addition, we have developed a robust RNAi methodology for targeting genes in D. gallinae that will be of value for studying genes of unknown function and validating potential control targets in D. gallinae.Graphical

Highlights

The avian haematophagous ectoparasite Dermanyssus gallinae, commonly known as the poultry red mite, causes significant economic losses to the egg-laying industry worldwide and represents a significant welfare threat
Core RNA interference (RNAi) components were selected to represent three RNAi pathways, namely the microRNA pathway (Argonaute-1, Dicer-1, loquacious, Drosha, Partner of Drosha (Pasha), Exportin-5), the small interfering RNA pathway (Argonaute-2, Dicer-2) and the P-element induced wimpy testis (Piwi)-interacting RNA pathway (Aubergine, Piwi, Argonaute-3); and RNA-directed RNA polymerase (RdRP), which is required for amplification of the RNAi silencing signal
Results miRNA and small interfering RNA (siRNA) pathways are present in the D. gallinae genome We used a systematic search for core RNAi genes involved in the siRNA pathway (Argonaute-2, Dicer2), miRNA pathway (Argonaute-1, Dicer-1, loquacious, Drosha, Pasha, Exportin-5) and Piwi-interacting RNA (piRNA) pathway (Aubergine, Piwi, Argonaute-3) in D. gallinae

Summary

Introduction

The avian haematophagous ectoparasite Dermanyssus gallinae, commonly known as the poultry red mite, causes significant economic losses to the egg-laying industry worldwide and represents a significant welfare threat. Poultry red mite [Dermanyssus gallinae (De Geer, 1778)], is an avian haematophagous ectoparasite with a worldwide distribution and a prevalence of 83% in European hen egg-laying facilities [1]. There are five life-cycle stages in D. gallinae: egg, larvae, protonymph, deutonymph and adult, with blood-feeding being a feature of only the latter three stages [2, 3]. This parasite lives off-host in the cracks and crevices in the hen facilities and only emerges to bite the host in darkness for a blood meal, which takes around 30–90 min, during which each mite consumes approximately 200 μg of. With the incidence of resistance against some acaricides increasing [12] and concerns over residues in food, multiple chemical treatments have been withdrawn from use in the European Union [2]

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