Biomarkers of cell-mediated immunity to bovine tuberculosis

Cell-Mediated Immunological Biomarkers and Their Diagnostic Application in Livestock and Wildlife Infected With Mycobacterium bovis

“…Non-DNA methods can be performed without advanced instrumentation, utilize more easily accessible samples such as blood and serum, and are generally more affordable than DNA-based tests (27,28). Hence, the focus of current bTB diagnostic research is host biomarkers with an emphasis on cytokine/chemokine (chemotactic cytokine) proteins and antibodies, in addition to the detection of cytokine RNA expression (5,24,58).…”

“…The ante mortem diagnosis of bTB in animals primarily relies on the detection of host CMI responses, most commonly with the use of protein and gene expression assays (5). Although the most widely used ancillary test, IGRA, in addition to the TST, can produce false negative results as the CMI responses required may diminish in advanced disease stages (anergy), while the humoral response increases (35,69).…”

“…A limitation of cytokine/chemokine protein assays can be the inability to detect high levels of the biomarker target due to, for example, binding saturation limits; therefore, mRNA responses and their detection may provide a more robust alternative (5). There are several studies that investigate cytokine/chemokine RNA expression to achieve diagnostic test objectives.…”

“…Mycobacterium bovis infection and the resulting disease, commonly referred to as bovine tuberculosis (bTB), affects a broad range of species including humans, domestic animals, and wildlife (1, 2). Although M. bovis, as the name suggests, mainly affects bovids including cattle (Bos taurus), bison (Bison bison), African and Asian buffaloes (Syncerus caffer and Bubalus bubalis), it has been isolated from numerous other mammals, compromising animal and human health worldwide with reports of this species on all continents except Antarctica (3)(4)(5). Infection of wildlife further impacts livestock health due to the development of maintenance and spillover hosts within wildlife populations, including badgers (Meles meles) in the United Kingdom (UK), African buffaloes in southern Africa, and farmed and wild cervids in the United States (US) (6)(7)(8).…”

“…In addition to the control challenges posed by infected wildlife species, bTB negatively affects wildlife-related industries, resulting in consequences for conservation, tourism, and game sales. Infection and disease in livestock and wildlife may lead to decreased productivity, trade restrictions, impacts on food security and zoonotic transmission, resulting in significant economic losses (5,12). Bovine tuberculosis costs the global cattle industry alone 3 billion US dollars annually (13).…”