Transcriptome analysis unraveled potential mechanisms of resistance to Haemonchus contortus infection in Merino sheep populations bred for parasite resistance

Authors: ZHANG, RUNFENG - Hubei University; LIU, FANG - Ocean University Of China; HUNT, PETER - Commonwealth Scientific And Industrial Research Organisation (CSIRO); Li, Congjun - Cj; ZHANG, LICHUN - Jilin Agricultural University; INGHAM, AARON - Commonwealth Scientific And Industrial Research Organisation (CSIRO); Li, Robert

Submitted to: Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2018
Publication Date: 1/24/2019
Citation: Zhang, R., Liu, F., Hunt, P., Li, C., Zhang, L., Ingham, A., Li, R.W. 2019. Transcriptome analysis unraveled potential mechanisms of resistance to Haemonchus contortus infection in Merino sheep populations bred for parasite resistance. Veterinary Research. 50:7. https://doi.org/10.1186/s13567-019-0622-6.
DOI: https://doi.org/10.1186/s13567-019-0622-6

Interpretive Summary: Gastrointestinal nematodes (GIN), such as the barber's pole worm Haemonchus contortus, represent a major health issue for livestock production systems worldwide. GIN infection causes great loss, both in impaired production and in control with anthelmintics. Moreover, current reliance on anthelmintic chemicals has resulted in great public concern for animal health/welfare and the contaminating residues in meat and dairy products. All of these factors have driven the development of effective and sustainable control strategies, including the development of genetically resistant populations. Characterizing transcriptome profiles that are differentially expressed for protective immune responses in sheep to parasitic infection is a critical step in understanding biological pathways and augmenting the biology of the host response to the parasite. A valuable model derived from two resource sheep flocks developed by selection and assortive mating over the past 40 years for genetic resistance or susceptibility to Haemonchus was used in this study to attempt to understand molecular mechanism of host resistance. The findings from this study should facilitate the development of GIN resistant sheep lines.

Technical Abstract: Haemonchus contortus is one of the most pathogenic gastrointestinal nematodes in small ruminants. To understand molecular mechanisms underlying host resistance to this parasite, we used RNA-sequencing technology to compare the transcriptomic response of the abomasal tissue, the site of the host-parasite interaction, of Merino sheep bred to be either genetically resistant or susceptible to Haemonchus infection. Two different selection flocks, the Haemonchus selection flock (HSF) and the Trichostrongylus selection flock (TSF), and each contains a resistant and susceptible line, were studied. A total of 127 and 726 genes displayed a significant difference in relative abundance between resistant and susceptible animals in response to a primary infection in HSF and TSF, respectively. Among them, 38 genes were significantly affected by infection in both flocks. Gene ontology (GO) enrichment of the differentially expressed genes identified in this study predicted the likely involvement of extracellular exosomes in the innate immune response to Haemonchus infection. Pathway and network analyses suggest that granulocyte adhesion and diapedesis and multiple pathways related to tissue repair and remodeling were involved in the development of host resistance. Our results offered a quantitative snapshot of changes in the host transcriptome induced by Haemonchus infection and provided novel insights into molecular mechanisms of host resistance.