Johne's disease is a chronic, granulomatous enteritis of ruminants and some wild-type species that is caused by infection with Mycobacterium avium spp. paratuberculosis (MAP). This inflammatory bowel disease (IBD) is characterized by a lengthy yet variable asymptomatic subclinical phase in which infected animals can transmit MAP to their progeny and herd mates; this is followed by a clinical phase characterized by chronic diarrhea, wasting, and eventually death. The impact of Johne's disease is particularly evident in the dairy and beef industries, where significant losses due to reduced productivity and fertility, mortality, and premature culling have been reported. Treatment and preventative management strategies have been difficult to implement and are often ineffective for preventing this IBD due to the pathogenic nature of MAP, and the duration of its subclinical phase. Individual resistance to Johne's disease is a heritable trait; therefore, it may be possible to selectively breed animals with enhanced disease resistance. To date, there have been few attempts to elucidate the genetic mechanisms involved in resistance to Johne's disease. Considering the polygenic nature of the disease, this task is inherently difficult, since there are likely dozens of loci scattered across the entire genome contributing small effects to disease resistance. Insight into the genetics of Johne's disease may be gained from research on Crohn's disease, a human IBD that parallels Johne's disease in many respects. Extensive epidemiological studies that have been conducted and validated in a number of different human populations have identified numerous susceptibility loci for Crohn's disease. Variants in the corresponding bovine genes may also contribute to resistance to Johne's disease. Therefore, the focus of this review is to examine the bovine immune response during MAP infection, highlight pathological similarities between Johne's disease and Crohn's disease, and lastly, discuss the likelihood of comparable genetic mechanisms and susceptibility loci existing between these diseases. © 2010 Nova Science Publishers, Inc. All rights reserved.
|Title of host publication||Veterinary Immunology and Immunopathology|
|Editors||Leon Neumann, Sophie Meier|
|Publisher||Nova Science Publishers|
|Number of pages||35|
|Publication status||Published - 2010|