Host–pathogen protein-protein interaction (PPI) data are very important information for illuminating infection mechanisms and for developing better prevention measures. However, host–pathogen PPI data are very scarce in most host–pathogen systems. Computational prediction of host–pathogen PPIs is an important strategy to fill in the gap. In this book, I systemically investigate host–pathogen protein-protein interactions using the H. sapiens–M. tuberculosis H37Rv system as the model host–pathogen system.