Functional Variants Surrounding Endothelin 2 Are Associated With Subspecies Infection.

Bovine paratuberculosis, caused by subspecies (), continues to impact the dairy industry through increased morbidity, mortality, and lost production. Although genome-wide association analyses (GWAAs) have identified loci associated with susceptibility to , limited progress has been made in identifying mutations that cause disease susceptibility. A 235-kb region on chromosome 3 (BTA3), containing a 70-kb haplotype block surrounding endothelin 2 (), has previously been associated with the risk of infection. is highly expressed in the gut and is involved in intracellular calcium signaling and a wide array of biological processes. The objective of this study was to identify putative causal mutations for disease susceptibility in the region surrounding in Holstein and Jersey cattle. Using sequence data from 10 Holstein and 10 Jersey cattle, common variants within the 70-kb region containing were identified. A custom SNP genotyping array fine-mapped the region using 221 Holstein and 51 Jersey cattle and identified 17 putative causal variants ( < 0.01) located in the 5' region of and a SNP in the 3' UTR ( = 0.00009) associated with infection. MicroRNA interference assays, mRNA stability assays, and electrophoretic mobility shift assays were performed to determine if allelic changes at each SNP resulted in differences in stability or expression. Two SNPs [ (G/A) and (G/T)] located within the promoter region of displayed differential binding affinity for transcription factors in binding sequences harboring the alternate SNP alleles. The luciferase reporter assay revealed that the transcriptional activity of the promoter was increased ( < 0.05) with the A allele for and the G allele for . These results suggest that the variants and are mutations that alter transcription and thus may alter susceptibility to infection in Holstein and Jersey cattle.