●Design of gene circuits: lessons from bacteria Wall, M. E., Hlavacek, W. S. & Savageau, M. A. Nature Reviews Genetics January (2004) doi: 10.1038/nrg1244. The construction of synthetic circuits for controlling gene expression is an exciting new area of biotechnology. As highlighted in this review, studies in bacteria have made an invaluable contribution towards understanding the functioning of gene circuits.

●Immunity to fungal infections Romani, L. Nature Reviews Immunology January (2004) Understanding fungal diseases is becoming ever more important, with increasing numbers of immunocompromised individuals who are susceptible to infection. This review discusses the complex range of host immune responses that are activated by fungi.

●Sequence of a symbiont Williamson, V. M. & Kaya, H. K. Nature Biotechnology November (2003) Reports on the recent sequencing of the bacterium Photorhabdus luminescens — an insect pathogen and nematode symbiont — which has identified a number of genes encoding potentially useful toxins and antibiotics.

●Taiwanese scientists find genetic link to SARS Chiu, Y. -T. Nature Medicine November (2003)

●Concerns raised over declining anti-infectives R&D Fox, J. L. Nature Biotechnology November (2003)

●TLR5 takes aim at bacterial propeller Reichart, J. -M. Nature Immunology December (2003) Unlike other Toll-like receptors, TLR5 targets a bacterial protein to initiate an immune response. This News and Views article describes recent work that reveals the details of how TLR5 interacts with flagellin — a key protein in bacterial propulsion.

●Prion disease: bridging the spleen–nerve gap Mabbot, N. A., Bruce, M. E. Nature Medicine December (2003) Highlights two recent papers that shed new light on the effects of prion diseases in lymphoid tissues.

●The causes and consequences of HIV evolution Holmes, E. C., Crandall, K. A., Posada, D. & Rambaut, A. Nature Reviews Genetics January (2004) This review discusses the factors underlying the rapid evolution of HIV and the implications of this for developing new stategies for prevention and treatment.

●Life on the inside for Mycobacterium tuberculosis McKinney, J. D. & Gomez, J. E. Nature Medicine November (2003) Describes recent microarray studies showing how changes in gene expression allow this bacterium to survive inhospitable conditions in host cells.