Martin J. Blaser, Denise Kirschner The equilibria that allow bacterial persistence in human hosts . Nature, Vol 449, j18, October 2007, pp 483-489

Niyaz Ahmed, of the Pathogen Evolution Laboratory, Centre for DNA Fingerprinting and Diagnostics, India, gives his comments on the article at facultyof1000.com

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This is a provocative yet legitimate proposal on how pathogenic bacteria adapt to their co-evolved hosts across a wide array of conditions linked to biology of both the host and pathogen, over huge evolutionary timescales. The authors focus on the concept that persistence represents finely negotiated, well balanced host- microbial interests, culminating in a long-term equilibrium whose maintenance requires a series of evolved, nested equilibria leading to the overall homeostasis. To support their assumption the authors harness observed pathobiology of three dreaded pathogens (H. pylori, S. typhi and M. tuberculosis). Based on the fact that genomic and biological features of these 'specialist' bacteria are quite diverse, authors generalize their model for other pathogens as well. If it is so, this model may also fit to commensals and other 'generalist' bacteria who might have accompanied humans in various capacities throughout their association. This dogma may therefore be relevant in understanding acquisition and/or attenuation of virulence with the change in human history and ecology. Although this is a largely speculative treatise, I am sure it will provide a foundation for future experimental evidence.

Joseph, I., Kirschner, D., A Model for the Study of Helicobacter Pylori Interaction with Human Gastric Acid Secretion . Journal of Theoretical Biology 228:55-80, 2004

Sud, D., Joseph, I., Kirschner, D., Predicting Efficacy of Proton Pump Inhibitors in Regulating Gastric Acid Secretion . Journal of Biological Systems, Vol. 12, No. 1, pg 1-34, 2004

Marino, S., Ganguli, S., Joseph, I.M.P., Kirschner, D.E., The Importance of an Inter-compartmental Delay in a Model for Human Gastric Acid Secretion . Bulletin of Math. Biology, 65:963-990,2003.

Joseph, I.M., Y. Zavros, J.L. Merchant, and D. Kirschner, A model for integrative study of human gastric acid secretion . J Appl Physiology 94, pg. 1602-1619, 2003.

Denise E. Kirschner, Reconstructing Microbial Pathogenesis ASM News Vol 67, Num. 11, pp. 566-573, 2001

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Blaser MJ and Kirschner D. Dynamics of Helicobacter pylori colonization in relation to the host immune response. PNAS, 96:8359-8364, 1999.

Kirschner D and Blaser M. The dynamics of Heliocobacter pylori infection of the human stomach. J Theor Biol 176:281-290, 1995.

ERRATA

Marino, S., Ganguli, S., Joseph, I.M.P., Kirschner, D.E., The Importance of an Inter-compartmental Delay in a Model for Human Gastric Acid Secretion . Bulletin of Math. Biology, 65:963-990, 2003.