Abstract
Johne's disease (JD), also known as paratuberculosis, is a severe production-limiting disease with significant economic and welfare implications for the global cattle industry. Caused by infection with Mycobacterium avium subspecies paratuberculosis (MAP), JD manifests as chronic enteritis in infected cattle. In addition to the economic losses and animal welfare issues associated with JD, MAP has attracted public health concerns with potential association with Crohn's disease, a human inflammatory bowel disease. The lack of effective treatment options, such as a vaccine, has hampered JD control resulting in its increasing global prevalence. The disease was first reported in 1895, but in recognition of its growing economic impact, extensive recent research facilitated by a revolution in technological approaches has led to significantly enhanced understanding of the immunological, genetic, and pathogen factors influencing disease pathogenesis. This knowledge has been derived from a variety of diverse models to elucidate host-pathogen interactions including in vivo and in vitro experimental infection models, studies measuring immune parameters in naturally-infected animals, and by studies conducted at the population level to enable the estimation of genetic parameters, and the identification of genetic markers and quantitative trait loci (QTL) putatively associated with susceptibility or resistance to JD. The main objectives of this review are to summarize these recent developments from an immunogenetics perspective and attempt to extract the principal and common findings emerging from this wealth of recent information. Based on these analyses, and in light of emerging technologies such as gene-editing, we conclude by discussing potential future avenues for effectively mitigating JD in cattle.
Highlights
Johne’s Disease—Global Context, Economic, and Zoonotic Relevance and ControlThe Food and Agriculture organization (FAO) estimates that in order to meet the growing demand from a world population projected to reach over 9 billion, annual meat production will need to increase by 41 million tons over 2019 production levels to 376 million tons by 2030 [1]
Predominance of a Th1-mediated immune response is observed during the early sub-clinical stage as extensive proliferation of CD4+ T cells with the resultant increased expression of pro-inflammatory cytokines like IFN-γ is detected in the ileal tissue of sub-clinically infected animals [87, 88], in peripheral blood mononuclear cells (PBMCs) [89], and PBMCs stimulated with Mycobacterium avium subspecies paratuberculosis (MAP) whole-cell sonicate [90]
By further defining tolerance as both quantitative and categorical trait, Zanella et al carried out a genome-wide association studies (GWAS) using the same data from the Settles et al study, and identified single nucleotide polymorphism (SNP) located on BTA1, BTA2, BTA6, and BTA15 to be significantly associated with tolerance to MAP infection [137]
Summary
The Food and Agriculture organization (FAO) estimates that in order to meet the growing demand from a world population projected to reach over 9 billion, annual meat production will need to increase by 41 million tons over 2019 production levels to 376 million tons by 2030 [1]. Leading the response to this demand is the bovine industry, and a number of recent changing trends in dairy production across the globe have been identified, with significant increases in the size of dairy herds [3], and a sectoral expansion in the EU after the abolition of milk quotas [4] These increasing cattle numbers and production levels, and other factors like recent changes toward increased animal housing in parts of the world, will exacerbate issues associated with the control of infectious diseases [5]. With the absence of vaccines and treatment options, the current control measures to reduce JD incidence are management-based; including employing a “test and cull strategy” to remove MAP infected animals from the herd [45], and enhancing on-farm biosecurity and surveillance measures to prevent MAP transmission within and between herds [46] In this regard, several countries have adapted voluntary JD eradication programmes [47].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
