Cross-species RNA-seq for deciphering host–microbe interactions

The human body is constantly exposed to microorganisms, which entails manifold interactions between human cells and diverse commensal or pathogenic bacteria. The cellular states of the interacting cells are decisive for the outcome of these encounters such as whether bacterial virulence programmes and host defence or tolerance mechanisms are induced. This Review summarizes how next-generation RNA sequencing (RNA-seq) has become a primary technology to study host–microbe interactions with high resolution, improving our understanding of the physiological consequences and the mechanisms at play. We illustrate how the discriminatory power and sensitivity of RNA-seq helps to dissect increasingly complex cellular interactions in time and space down to the single-cell level. We also outline how future transcriptomics may answer currently open questions in host–microbe interactions and inform treatment schemes for microbial disorders. Interactions between microorganisms and their hosts are highly context dependent and contribute to both normal tissue function and infectious disease pathology. In this Review, Westermann and Vogel describe how advances in RNA sequencing techniques are providing molecular insights into host–microbe interactions, including advances in cross-species and single-cell transcriptomics.