RNA-seq transcriptome analysis of peripheral blood from cattle infected with Mycobacterium bovis across an experimental time course

Bovine tuberculosis (BTB), caused by infection with members of the Mycobacterium tuberculosis complex—particularly Mycobacterium bovis, is a major endemic disease affecting cattle populations worldwide, despite the implementation of stringent surveillance and control programmes in many countries. The development of high-throughput functional genomics technologies, including RNA sequencing (RNA-seq), has enabled detailed analysis of the host transcriptome to M. bovis infection, particularly at the macrophage and peripheral blood level. In the present study, we have analysed the transcriptome of bovine whole peripheral blood samples collected at -1 wk pre-infection, and +1 wk, +2 wk, +6 wk, +10 wk and +12 wk post-infection time points. Differentially expressed genes were catalogued and evaluated at each post-infection time point relative to the -1 wk pre-infection time point and used for the identification of putative candidate host transcriptional biomarkers for M. bovis infection. Differentially expressed gene sets were also used for examination of cellular pathways associated with the host response to M. bovis infection, construction of de novo gene interaction networks enriched for host DE genes, and time series analyses to identify functionally important groups of genes displaying similar patterns of expression across the infection time course. A notable outcome of these analyses was identification of a 19-gene transcriptional biosignature of infection consisting of genes increased in expression across the time course from +1 wk, to +12 wk post-infection.