Authors

Discussion

Teladorsagia circumcincta is a common parasitic nematode of the sheep abomasum. Host immunity is acquired through repeated exposure. The immune response, pathology and clinical outcome vary greatly between animals. This project aimed to: 1) understand how sheep respond to worm infection; 2) identify genes associated with the response; 3) identify variation within those genes which may contribute to resistance. T helper cell (Th)1 and Th17 activation is associated with susceptibility (low antibody, high worm numbers) while a Th2 response is linked with resistance (high antibody levels and clearance of infection). The Th cell transcription factors were sequenced; and splice variants were identified, which potentially effect protein structure. RT-qPCR of mucosa from Resistant and Susceptible lambs demonstrated a significant difference in expression of GATA3 (fold change [FC] 2.06, P-value < 0.001), RORC2 (FC -1.41, P-value 0.01) and RORC2v1 (FC -1.30, P-value 0.03). Copy number analysis of GATA3 and RORC2v1 in experimentally-infected lambs identified significant correlation of genotype with phenotype, implicating these genes as potential selection markers for breeding programmes.