Cheaters lose. Tuberculosis settles into the lungs. Helicobacter pylori, the microbe causing ulcers, burrows into the stomach where it thrives on acids. And Salmonella typhi takes up residence in the gallbladder. All of these organisms can persist in our bodies for decades. What explains their success"
A new mathematical model, devised by a microbiologist renowned for his study of H. pylori and a mathematician, provides the framework for understanding how persistent microbes obtain equilibrium with their human hosts. The multi-scale model, published in the October 18, 2007, issue of the journal Nature, is based on the idea that certain microbes and humans evolved together and along the way established complex strategies that enabled them to co-exist. These strategies are contingent in part on human population size.
The model helps explain the rules that govern the transmission of microbes and how they have operated in human history, says Martin J. Blaser, M.D., the Frederick King Professor and Chair of the Department of Medicine, and Professor of Microbiology at New York University School of Medicine. He and Denise Kirschner of the University of Michigan Medical School, Ann Arbor, are authors of the study. The model uses game theory, developed by Nobel prize-winning mathematician John Nash, the subject of the book and movie A Beautiful Mind, to describe a particular type of equilibrium.
The model can be used to better understand microbial responses to a changing human world, says Dr. Blaser. Based on their formulations, our biological future will probably be filled with some “pretty bad epidemics,” says Dr. Blaser. “Our model predicts that as effective population size increases and as immunodeficiency increases due to the spread of HIV infection, and an aging population, there will be more virulent organisms. This is bad news for us.”
Through the course of human evolution, Drs. Blaser and Kirschner propose that three classes of persistent microbes have evolved, each employing a different biological strategy to avoid being eliminated quickly by their human hosts. TB, H. pylori, and Salmonella are an example of each class. Any microbe that was “cheating” the system, in other words, tried to expand its territory in the body, wouldn’t survive because it would likely kill its host.
According to their theory, small populations select for certain kinds of microbial agents. More than 50,000 years ago, when humans lived as hunter-gatherers in small, isolated groups, the majority of microbes were transmitted within families or were those that would emerge late in life. Microbes that were not lethal were favored because there wasn’t a large reservoir of people to infect. Any microbe that killed off its hosts, wouldn’t have survived itself. H. pylori evolved during this time.
As population size increased and humans became less isolated, organisms that had perfected ways to hide in the body for decades, such as TB and Salmonella typhi, and then suddenly reactivate or get transmitted, evolved. These organisms could afford to induce more disease early in life because they had mechanisms to sustain themselves in human populations.
As even larger societies developed, more virulent organisms, such as measles, emerged because the population could permit the virus to spread. Our most recent epidemics, including influenza in the early 20th century and AIDS today, involve organisms that can kill millions because these highly virulent organisms have a huge pool of people to infect, and still be transmitted.
“We did not make the laws of nature,” says Dr. Blaser. “Even though we may not like them, we need to understand them to better control infectious diseases.”
Pamela McDonnell | EurekAlert!
Nanoparticle Exposure Can Awaken Dormant Viruses in the Lungs
16.01.2017 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Cholera bacteria infect more effectively with a simple twist of shape
13.01.2017 | Princeton University
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.
The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
17.01.2017 | Earth Sciences
17.01.2017 | Materials Sciences
17.01.2017 | Architecture and Construction