John_Hopkins_Tcircumcincta_Archive

Illumina Solexa digital gene expression and Affymetrix Ovine Gene 1.1 ST Array data of Blackface sheep with defined parameters of resistance and susceptibility to the parasitic nematode, Teladorsagia circumcincta.

Teladorsagia circumcincta is a common parasitic nematode of the sheep abomasum. Immunity is acquired through repeated exposure to the parasite. The immune response, pathology and clinical outcome vary greatly between animals. The aims of this project are: 1) understand how sheep respond to worm infection; 2) understand and identify genes associated with the response; 3) identify variation within those genes which may contribute to resistance.This study exploited Blackface lambs that varied in their resistance to the abomasal nematode parasite, Teladorsagia circumcincta. Infection of these lambs over 3 months identified susceptible (high adult worm count, high faecal egg count and low IgA antibody) and resistant animals that had excluded all parasites. Previous work had shown that susceptibility and resistance is dependent on the differential immune response to the parasite, which occurs within the abomasal (gastric) lymph node (ALN) that drains the site of infection. The Affymetrix ovine gene array was used to interrogate the transcriptome of the ALN to identify genes and physiological pathways associated with resistance. We used a bovine RT-qPCR array of 84 genes to validate the gene array, and also report digital gene expression analysis on the same tissues, reanalysed using the Oar v3.1 sheep genome assembly. These analyses identified Humoral Immune Response, Protein Synthesis, Inflammatory Response and Hematological System Development and Function as the two top-ranked networks associated with resistance. Central genes within these networks were IL4, IL5, IL13RA2 and in particular IL13, which confirmed that differential activation of Th2 polarized responses is critical to the resistance phenotype. Furthermore, in resistant sheep there was up-regulation of genes linked to control and suppression of inflammation. The identity of differentially-expressed chemokines and receptors in the resistant and susceptible sheep also begins to explain the cellular nature of the host response to infection. This work will greatly help in the identification of candidate genes as potential selectable markers of genetic resistance.

1. Beraldi, D., B.H. Craig, S.C. Bishop, J. Hopkins and J.M. Pemberton. (2008). Phenotypic analysis of host-parasite interaction in lambs infected with Teladorsagia circumcincta. Int J Parasitol. 38; 1567-1577. PMID: 18589425, doi: 10.1016/j.ijpara.2008.04.011.
2. Pemberton, J. M., D. Beraldi, B. H. Craig and J. Hopkins. (2011) Digital gene expression analysis of gastrointestinal helminth resistance in Scottish blackface lambs. Molecular Ecology 20, 910–919. PMID: 21324010, doi: 10.1111/j.1365-294X.2010.04992.x.
3. Gossner, A.G., H. Wilkie, A. Joshi and J. Hopkins. (2013). Exploring the abomasal lymph node transcriptome for genes associated with resistance to the sheep nematode Teladorsagia circumcincta. Veterinary Research 44: 68. PMID: 23927007, doi: 10.1186/1297-9716-44-68.. doi:10.1371/journal.pone.0168194.