Gene silencing by RNA interference in the ectoparasitic mite, Psoroptes ovis

Edward J Marr,Neil D Sargison,Stewart T G Burgess,Harry W Wright,Alasdair J Nisbet

doi:10.1186/s13567-018-0608-9

Abstract

The presence of components of the RNA interference (RNAi) pathway in Psoroptes ovis, an ectoparasitic mite responsible for psoroptic mange, was investigated through interrogation of the P. ovis genome. Homologues of transcripts representing critical elements for achieving effective RNAi in the mite, Tetranychus urticae and the model organisms Caenorhabditis elegans and Drosophila melanogaster were identified and, following the development of a non-invasive immersion method of double stranded RNA delivery, gene silencing by RNAi was successfully demonstrated in P. ovis. Significant reductions in transcript levels were achieved for three target genes which encode the Group 2 allergen (Pso o 2), mu-class glutathione S-transferase (PoGST-mu1) and beta-tubulin (Poβtub). This is the first demonstration of RNAi in P. ovis and provides a mechanism for mining transcriptomic and genomic datasets for novel control targets against this economically important ectoparasite.

Highlights

Psoroptic mange, caused by infestation with the ectoparasitic mite Psoroptes ovis, Hering, 1838, is a disease of significant welfare and economic importance with a global presence
Identification of RNA interference (RNAi) pathway genes in the P. ovis genome Homologous sequences to the major RNAi pathway components were identified in the P. ovis genome, including sequences encoding genes involved in RNA induced silencing complex (RISC) formation, small RNA biosynthesis and secondary amplification of small RNAs (Table 1)
Homologues of several known RNAi pathway components were detected in the genome (Table 1) and the demonstration of gene silencing by RNAi shown here validated the functionality of the pathway in P. ovis

Summary

Introduction

Psoroptic mange, caused by infestation with the ectoparasitic mite Psoroptes ovis, Hering, 1838, is a disease of significant welfare and economic importance with a global presence. The first draft genome for P. ovis was recently published [18] providing a valuable resource for molecular studies into this ectoparasite This new genome resource can be exploited for the identification of novel vaccine and diagnostic candidates and for molecular genetic studies into the development of acaricide resistance. We interrogated the P. ovis genome to identify components of the RNAi machinery and based on the outcomes of that process and previous studies in other closely related astigmatid mites [19, 20], we sought to develop a non-invasive means of RNAi in P. ovis These new tools provide a crucial resource for the identification and validation of novel means of control for this economically important ectoparasite

Methods

Results

Conclusion