PRESS-NEWS.org - Press Release Distribution
PRESS RELEASES DISTRIBUTION

From friend to foe: How benign bacteria evolve to virulent pathogens

2013-12-13
(Press-News.org) Contact information: Isabel Gordo
igordo@igc.gulbenkian.pt
351-214-407-915
Public Library of Science
From friend to foe: How benign bacteria evolve to virulent pathogens

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."

For their study, the scientists studied initially benign E. coli bacteria that were continuously confronted with macrophages, which are part of our immune system and can swallow and digest bacteria. They grew a mix of bacteria and macrophages in a liquid culture (a glass bottle that contains a nutritious broth). Once a day, they diluted the mix, and every other day they took a sample of the bacteria for further analysis. As a control, they grew, diluted, and analyzed bacteria from the same ancestral strain but grown without macrophages.

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".



INFORMATION:

EMBARGO: December 12th 2013, 2pm PST/5pm EST

Please mention PLOS Pathogens as the source for this article

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

IN YOUR COVERAGE PLEASE PROVIDE THIS LINK TO THE FREELY AVAILABLE PAPER: http://dx.plos.org/10.1371/journal.ppat.1003802 (Link will go live upon publication)



ELSE PRESS RELEASES FROM THIS DATE:

Physical activity may slow kidney function decline in patients with kidney disease

2013-12-13
Physical activity may slow kidney function decline in patients with kidney disease 60 million people globally have chronic kidney disease. Washington, DC (December 12, 2013) — Increased physical activity may slow kidney function decline in patients with kidney disease, ...

Diet and physical activity may affect one's risk of developing kidney stones

2013-12-13
Diet and physical activity may affect one's risk of developing kidney stones Even small amounts of exercise provide benefits Washington, DC (December 12, 2013) — Even small amounts of physical activity may decrease the risk of developing kidney stones, according ...

Astronomers discover first noble gas molecules in space

2013-12-13
Astronomers discover first noble gas molecules in space Noble gas molecules have been detected in space for the first time in the Crab Nebula, a supernova remnant, by astronomers at UCL. Led by Professor Mike Barlow (UCL Department of Physics & Astronomy) ...

Using air transportation data to predict pandemics

2013-12-13
Using air transportation data to predict pandemics Computational model demonstrates how disease spreads in a highly connected world Computational work conducted at Northwestern University has led to a new mathematical theory for understanding the global spread ...

Many older Americans rely on people, devices, other strategies to get by

2013-12-13
Many older Americans rely on people, devices, other strategies to get by ANN ARBOR— Only about a third of Americans ages 65 and older are fully able to take care of themselves and go about their daily lives completely independently, according to a new study ...

James Bond's preference for shaken martinis may be due to alcohol-induced tremor, say experts

2013-12-13
James Bond's preference for shaken martinis may be due to alcohol-induced tremor, say experts Famous spy drinks over 4 times the recommended weekly alcohol limit James Bond's alcohol consumption may explain why he prefers his martinis "shaken, not ...

Should your surname carry a health warning?

2013-12-13
Should your surname carry a health warning? Research: The Brady Bunch? New evidence for nominative determinism in patients' health: Retrospective, population based cohort study Patients named Brady could be at an increased risk of requiring a pacemaker compared ...

Is laughter really the best medicine?

2013-12-13
Is laughter really the best medicine? Food for thought: Laughter and MIRTH (methodical investigation of risibility, therapeutic and harmful): Narrative synthesis Laughter may not be the best medicine after all and can even be harmful to some patients, suggests ...

Quantum waves at the heart of organic solar cells

2013-12-13
Quantum waves at the heart of organic solar cells By using an ultrafast camera, scientists say they have observed the very first instants following the absorption of light into artificial yet organic nanostructures and found that charges not only formed rapidly ...

How Wagner's operas held secrets of his disabling migraines and headaches

2013-12-13
How Wagner's operas held secrets of his disabling migraines and headaches Medical histories: 'Compulsive plague! Pain without end!' How Richard Wagner played out his migraine in the opera Siegfried In a paper published in the Christmas edition of The BMJ, researchers ...

LAST 30 PRESS RELEASES:

Interactive apps, AI chatbots promote playfulness, reduce privacy concerns

How NIL boosts college football’s competitive balance

Moffitt researchers develop machine learning model to predict urgent care visits for lung cancer patients

Construction secrets of honeybees: Study reveals how bees build hives in tricky spots

Wheat disease losses total $2.9 billion across the United States and Canada between 2018 and 2021

New funding fuels development of first potentially regenerative treatment for multiple sclerosis

NJIT student–faculty team wins best presentation award for ant swarm simulation

Ants defend plants from herbivores but can hinder pollination

When the wireless data runs dry

Inquiry into the history of science shows an early “inherence” bias

Picky eaters endure: Ecologists use DNA to explore diet breadth of wild herbivores

Study suggests most Americans would be healthier without daylight saving time

Increasing the level of the protein PI31 demonstrates neuroprotective effects in mice

Multi-energy X-ray curved surface imaging-with multi-layer in-situ grown scintillators

Metasurface enables compact and high-sensitivity atomic magnetometer

PFAS presence confirmed in the blood of children in Gipuzkoa

Why do people believe lies?

SwRI installs private 5G network for research, development, testing and evaluation

A new perspective in bone metabolism: Targeting the lysosome–iron–mitochondria axis for osteoclast regulation

Few military spouses use formal support services during, after deployment

Breakthrough in the hunt for light dark matter: QROCODILE project reveals world-leading constraints

2D x-ray imaging technique reveals hidden processes in CO2 electrolyzers

Rational high entropy doping strategy via modular in-situ/post solvothermal doping integration for microwave absorption

Circular Economy has been officially included in the ESCI

Recent advances in exciton-polariton in perovskite

Efficacy and safety of GLP-1 RAs in children and adolescents with obesity or type 2 diabetes

Over-the-counter sales of overdose reversal drug naloxone decline after initial surge

Global trends and disparities in social isolation

Country of birth, race, ethnicity, and prenatal depression

Kissick Family Foundation, Milken Institute announce $2 million in funding for frontotemporal dementia research and new call for proposals

[Press-News.org] From friend to foe: How benign bacteria evolve to virulent pathogens