Subversion of eukaryotic host cell pathways enables microorganisms to control cell responses, allowing avoidance of host defences and establishment of a niche in which to grow. To highlight advances in our understanding of the mechanisms by which microorganisms tailor cellular pathways to their own needs, Nature Reviews Microbiology and Nature Cell Biology present a joint Focus issue containing a specially commissioned set of articles that highlight some of the key pathways in host cells that are subverted by intracellular microorganisms. The topics covered range from how bacteria have adapted to replicate and grow within a host cell and avoid intracellular antimicrobial defences, to how viruses have co-opted the host cell's endocytic machinery and ubiquitin system during infection and viral replication. The mechanisms by which pathogenic bacteria subvert innate and adaptive immune responses are considered and we ask whether commensal bacteria subvert or evade these responses. The Focus also features the events associated with the remodelling of host red blood cells that are triggered by secreted effectors of malaria parasites. The articles are available free to download for 2 months. An accompanying Web focus draws together the most relevant recent publications from the Nature Publishing Group (http://www.nature.com/focus/microbial).

Also in this month's issue, on page 375, Bruce Logan highlights the recent advances that have led us to a point at which microbial fuel cells are increasingly being seen as a viable source of renewable energy. Identification of the mechanisms that underlie electricity production by exoelectrogenic bacteria, together with a better understanding of microbial fuel cell architecture, has led to improved power production.