- Isabella Ferraro, Agriculture and Natural Resources, University of Delaware
- Amy Biddle, , University of Delaware
Identifying Uncharacterized Proteins Associated with Anthelmintic Resistance in Cyathostomins
Equine cyathostomins are a group of small strongyles that make up some of the most prevalent intestinal parasites known to horses today. Ivermectin, a popular anthelmintic in horses, has become increasingly resistant, with a fecal egg count reduction of about 95%, which is expected to increase due to overuse. The purpose of this study is to identify uncharacterized proteins that were found in a prior RNA- Seq experiment to measure gene expression in larvae that survived treatment of ivermectin at three different levels along with untreated controls. By identifying these uncharacterized proteins by finding potential matches in other nematode species, we can understand possible mechanisms of resistance in these cyathostomins.
Using BLAST, (Basic Local Alignment Search Tool) matches were discovered within other species by comparing the length, the percentage match, and the e-values. By using this method for the low, medium, and high anthelmintic levels, potential matches were found for most of the proteins. The proteins that were of most interest were membrane transporters and cytoskeleton structure and organization proteins. 10 membrane transporters and 3 metal ion transporters were found to be more highly expressed in the high dose than controls. 1 cytoskeleton gene was down-regulated, which shuts off the pathway for ivermectin to infiltrate the nematode. 2 cuticle proteins were up-regulated which indicates the structural component of the cuticle was enriched to prevent ivermectin stimulation. This supports prior hypotheses suggesting that up-regulation of transporter proteins, such as ABC transporters, contribute to ivermectin efflux out of the parasite, therefore limiting the time the drug has to act in the parasite. These results point to specific mechanisms enabling survival of cyathostomins, which could be developed into more effective drug targets to reduce resistance.