Creating a free account will enable you to subscribe to our daily and weekly email newsletters, as well as customize your reading experience to show only the categories most relevant to you.
Signing up only take a few minutes, so why not give it a try and see what you've been missing out on.
Bacteria can evolve rapidly to adapt to environmental change. When the "environment" is the immune response of an infected host, this evolution can turn harmless bacteria into life-threatening pathogens. A study published on December 12 in PLOS Pathogens provides insight into how this happens.
Isabel Gordo and colleagues from the Instituto Gulbenkian de Ciencia in Oeira, Portugal, have for the first time devised an experimental system to observe and study the evolution of bacteria in response to encounters with cells of the mammalian immune system. They found that in less than 500 bacterial generations (or 30 days), the bacteria became more resistant to being killed by immune cells and acquired the ability to cause disease in mice.
"Escherichia coli bacteria show an extraordinary amount of diversity: Many are benign commensal bacteria, but some are deadly pathogens", says Isabel Gordo. "It is thought that many strains of E. coli that cause disease in humans evolved from commensal strains. We thought that experimental evolution would be a powerful tool to directly observe some of the steps E. coli may take in the transition from commensalism to pathogenesis."
From day four on, bacteria that had been exposed to macrophages started to show changes in their phenotype (their appearance), whereas such changes were never observed in the controls. The selective pressure imposed by the presence of the macrophages prompted changes in the bacteria that were consistently observed in six independent experimental series. The changes affected the phenotype of the bacteria (with new variants forming either "small colonies" or "mucoid colonies"), their fitness, and their genetic make-up.
When the scientists looked at the interaction between new variant bacteria and macrophages more closely, they found that the small colony variants were more resistant to being digested by macrophages than the ancestral strain, and the mucoid variant was less likely to be gobbled up. When they infected mice with mucoid variant bacteria, they also found that the variants have increased ability to cause disease in mice.
"We demonstrate", the scientists say, "that E. coli can adapt to better resist macrophages within a few hundred generations, and that clones with morphologies and traits similar to those of pathogenic bacteria rapidly emerge".
Funding: The research leading to these results has received funding from the European Research Council under the European Community's Seventh Framework Programme (FP7/2007)/ERC grant agreement no 260421 – ECOADAPT. IG acknowledges the salary support of LAO/ITQB & FCT. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interests: The authors have declared that no competing interests exist.
Citation: Miskinyte M, Sousa A, Ramiro RS, de Sousa JAM, Kotlinowski J, et al. (2013) The Genetic Basis of Escherichia coli Pathoadaptation to Macrophages. PLoS Pathog 9(12): e1003802. doi:10.1371/journal.ppat.1003802
Article adapted by Medical News Today from original press release. Click 'references' tab above for source.
Visit our Infectious Diseases / Bacteria / Viruses category page for the latest news on this subject.
Please use one of the following formats to cite this article in your essay, paper or report:
Pathogens, PLOS. "From friend to foe: How benign bacteria evolve to virulent pathogens." Medical News Today. MediLexicon, Intl., 17 Dec. 2013. Web.
11 Mar. 2014. <http://www.medicalnewstoday.com/releases/270186>
Pathogens, P. (2013, December 17). "From friend to foe: How benign bacteria evolve to virulent pathogens." Medical News Today. Retrieved from
Please note: If no author information is provided, the source is cited instead.
If you write about specific medications, operations, or procedures please do not name healthcare professionals by name.
For any corrections of factual information, or to contact our editorial team, please use our feedback form. Please send any medical news or health news press releases to:
Note: Any medical information published on this website is not intended as a substitute for informed medical advice and you should not take any action before consulting with a health care professional. For more information, please read our terms and conditions.
This page was printed from: http://www.medicalnewstoday.com/releases/270186.php
Visit www.medicalnewstoday.com for medical news and health news headlines posted throughout the day, every day.
© 2004-2014 All rights reserved. MNT (logo) is the registered trade mark of MediLexicon International Limited.