Gene expression profiling of the host response to Mycobacterium bovis infection in cattle

Bovine tuberculosis (BTB), caused by Mycobacterium bovis, continues to pose a threat to livestock worldwide and, as a zoonotic infection, also has serious implications for human health. The implementation of comprehensive surveillance programmes to detect BTB has been successful in reducing the incidence of infection in many countries, yet BTB has remained recalcitrant to eradication in several EU states, particularly in Ireland and the UK. There are well-recognized limitations in the use of the current diagnostics to detect all infected animals and this has led to renewed efforts to uncover novel diagnostic biomarkers that may serve to enhance the performance of the tests. Studies of single immunological parameters have so far been unable to unlock the complexities of the immune response to mycobacterial infection. However, the development of high-throughput methods including pan-genomic gene expression technologies such as DNA microarrays has facilitated the simultaneous identification and analysis of thousands of genes and their interactions during the immune response. In addition, the application of these new genomic technologies to BTB has identified pathogen-associated immune response signatures of host infection. The objective of these investigations is to understand the changing profile of immune responses throughout the course of infection and to identify biomarkers for sensitive diagnosis, particularly during the early stages of infection. Transcriptional profiling via microarray and more recently via next-generation sequencing technologies may lead to the development of specific and sensitive diagnostics for M. bovis infection and will enhance the prospect of eradication of tuberculosis from cattle populations.