Sir

I would like to add my strong support to your Editorial “Infection biology” (Nature 441, 255–256; 200610.1038/441255a) praising the innovative approaches to infection biology described in the US National Academies report Treating Infectious Diseases in a Microbial World. We need to move on from viewing infection as the rather exotic province of a handful of specialized 'virulence genes' carried by a small group of pathogenic organisms, to an appreciation of our true complicity in the microbial world.

The initial encounter of a pathogen with the host immune system involves a bewilderingly complex interchange of signals between the two organisms that sets in train a multiplicity of respective adaptive responses. In addition to immune cells and the pathogen itself, our personal complement of 1.5 kg of intestinal microflora is likely to be a major arbiter in this encounter. Commensal microbes are important in maintaining the networks regulating the innate immune response: they are certainly important in distributing genes mediating resistance to antibiotics, and they may also regulate the way in which we metabolize treatment drugs.

Systems biology provides a framework in which to address this complexity. Moving towards the rational design of novel antimicrobials and novel vaccines — particularly novel antimicrobials and vaccines that can be applied in synergistic combinations — involves digestion of huge amounts of information generated by increasingly high-throughput approaches to microbiology, immunology, genetics and population biology. To make sense of this requires a combination of traditional biology skills with the expertise of mathematicians and computer scientists.

In addition to improving our weapons in the 'war' against selected pathogens, a deeper understanding of the ways in which we interact with microbes is crucial in combating a wide range of diseases and disorders. The population of microbes that has a vested interest in a healthy human population is very much larger than that which seeks our destruction. Systems biology may help us turn this fact to our advantage.