Silencing of essential genes by RNA interference inHaemonchus contortus

Abstract

SUMMARYIn this study we assessed three technologies for silencing gene expression by RNA interference (RNAi) in the sheep parasitic nematodeHaemonchus contortus. We chose as targets five genes that are essential inCaenorhabditis elegans(mitr-1, pat-12, vha-19, glf-1andnoah-1), orthologues of which are present and expressed inH. contortus, plus four genes previously tested by RNAi inH. contortus(ubiquitin, tubulin, paramyosin, tropomyosin). To introduce double-stranded RNA (dsRNA) into the nematodes we tested (1) feeding free-living stages ofH. contortuswithEscherichia colithat express dsRNA targetting the test genes; (2) electroporation of dsRNA intoH. contortuseggs or larvae; and (3) soaking adultH. contortusin dsRNA. For each gene tested we observed reduced levels of mRNA in the treated nematodes, except for some electroporation conditions. We did not observe any phenotypic changes in the worms in the electroporation or dsRNA soaking experiments. The feeding method, however, elicited observable changes in the development and viability of larvae for five of the eight genes tested, including the ‘essential’ genes,Hc-pat-12, Hc-vha-19andHc-glf-1. We recommend theE. colifeeding method for RNAi inH. contortusand provide recommendations for future research directions for RNAi in this species.