Bovine TB in livestock and wildlife: what's in the genes?

Bovine tuberculosis (BTB) is a chronic, infectious disease found in domestic livestock and wildlife. It is caused predominantly by Mycobacterium bovis, which forms part of the Mycobacterium tuberculosis complex. BTB has serious implications for the movement of animals and animal products, biodiversity, and public health and is of significant economic concern. The existence of wildlife maintenance hosts makes it extremely difficult to eradicate BTB, even when established control strategies are in place, creating the need for alternative methods for controlling this disease. There are multiple factors that influence the outcome of infection by a pathogen, one of which is the host's genome. The identification of genetic variants involved in the susceptibility to BTB would supply a new selection of potential drug targets as well as the possibility for the breeding of animals with greater disease resistance. In this review, we collate the results of the BTB heritability and association studies performed in cattle and wildlife, discuss considerations and other methodologies (such as gene expression work) to be taken into account when performing genetic studies, and make some recommendations for future work in this area.