Short communication: refinement of genetic regions associated with Mycobacterium avium subspecies paratuberculosis tissue infection and tolerance to Johne's disease.

Johne's disease is a highly transmissible bacterial disease caused by Mycobacterium avium ssp. paratuberculosis (MAP). The objective of this study was to refine the locus associated with MAP tissue infection and the locus associated with tolerance to Johne's disease. Using a genome-wide association analysis, single nucleotide polymorphisms associated with MAP tissue infection and tolerance to Johne's disease on Bos taurus autosome (BTA)3 and BTA15, respectively, have previously been identified. A 235-kb region on BTA3 was evaluated with 42 single nucleotide polymorphisms, and a 193-kb region on BTA15 was evaluated with 54 single nucleotide polymorphisms in a group of 209 Holstein cows. Using a single marker association analysis and haplotype tests, we refined a region of 10.6 kb on BTA3 as being associated with MAP tissue infection and a region of 6.5 kb on BTA15 as being associated with tolerance to Johne's disease.