A bioinformatician considers the general applicability of host-pathogen computer simulations

Computer simulations can help explain evolutionary phenomena such as co-evolution and the emergence of robustness. Unlike traditional methods of analysis, such simulations can incorporate detailed representations of environmental antagonisms — such as the pressure that parasites exert on the evolution of their hosts.

This is what Marcel Salathé of ETH Zurich in Switzerland and Orkun Soyer of the University of Trento, Italy, recently analysed at the molecular level. By using computer simulations based on mathematical models, they showed how robust signalling networks may evolve in parasite-infested cells (M. Salathé and O. S. Soyer Mol. Syst. Biol. 4, 202; 2008). In their simulations, signalling networks exhibited increasing redundancy in response to parasites, to the point that a node could be entirely removed without affecting network function. It seems that network redundancy may be a signature of parasitism present or past.

The paper is an exciting invitation to take a computational approach to evolutionary questions, by including more detailed mathematical representations. One could, for example, extend the host-parasite model to incorporate not just protein sequences, but also the ways in which genomic variation is generated, and see how everything plays out.

The approach could be generalized. National security studies, for example, might examine when and how attempts to infiltrate terrorist networks might actually make them more robust. And perhaps Salathé and Soyer's approach could be used to find ways of using environmental interference to reduce the robustness of disease networks, such as cancer signalling pathways, by examining their antagonistic interactions with therapeutic agents.

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