The microRNAome of Strongylus vulgaris larvae and their excretory/secretory products with identification of parasite-derived microRNAs in horse arterial tissue.

This study explores the different types of microRNA expressed by the parasite Strongylus vulgaris during its fourth and fifth larval stages, and whether these can be detected in the parasite’s excretory or secretory products, or in the horse arterial tissue that the parasite inhabits. It found that there are significant differences in microRNA populations between the larvae and the waste products, and among the larvae of different sexes and different stages. Only one type of parasite-derived microRNA was occasionally detectable in the horse arterial tissue.

Study Objectives and Methods

• The focus of this study was the equine bloodworm, Strongylus vulgaris, and the microRNAs (short stretches of RNA molecules that play key roles in regulating gene expression) that it produces and releases.
• The researchers’ aim was to catalog all the microRNAs produced by the S. vulgaris during its fourth and fifth larval stages, and to investigate how these vary according to the sex and stage of the larvae.
• They also sought to determine whether these microRNAs could be identified in the waste products produced by the larvae and in the arterial tissue of the horse where the parasite tends to live.
• The researchers collected larvae of S. vulgaris from infected foals and categorized them by sex and stage. They also collected arterial tissue samples from the horses’ cranial mesenteric artery – a known site of infestation by this parasite.
• Using a technique called small RNA sequencing, they were then able to identify and catalog the microRNAs present in the larvae and the waste products.

Study Findings

• The study identified a total of 142 microRNAs in the larvae, and 136 in the waste products.
• It found significant differences in the abundance of these microRNAs between the larvae and the waste products.
• Within the larvae, there were also differences in microRNA abundance depending on the sex and stage of the larvae. For example, there were significant differences between the female larvae in their fifth stage and the males in their fifth stage, as well as between the fourth-stage larvae and all the fifth-stage larvae.
• However, among the excretory/secretory products (waste products), there were differentially abundant microRNAs across all the groups.
• The abundance of selected microRNAs was validated using a technique called quantitative real-time PCR.
• However, only one type of parasite-derived microRNA could be detected in the horse arterial tissue samples, and then only very occasionally and in very low levels.

Study’s Impact

• This research is valuable because it provides the first comprehensive cataloguing of the microRNAs produced by the parasite S. vulgaris. This could offer valuable insights into the biology of this parasite and may provide new opportunities for controlling its infestation in horses.
• The study also reveals how the expression of these microRNAs varies according to the sex and stage of the larvae, which again might suggest new strategies for managing infestations.
• However, the findings of this study suggest that the released microRNAs of the bloodworm are not consistently present in the host arterial tissue, limiting their use as a potential diagnostic tool.