Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists Unlock Evolution of Cholera, Identify Strain Responsible for Early Pandemics That Killed Millions

09.01.2014
Working with a nearly 200-year-old sample of preserved intestine, researchers at McMaster University and the University of Sydney have traced the bacterium behind a global cholera pandemic that killed millions – a version of the same bug that continues to strike vulnerable populations in the world’s poorest regions.

Using sophisticated techniques, the team has mapped the entire genome of the elusive 19th century bacterium. The findings are significant because, until now, researchers had not identified the early strains of cholera, a water-borne pathogen. The discovery significantly improves understanding of the pathogen’s origin and creates hope for better treatment and possible prevention.


McMaster University

A preserved intestine from a male victim of cholera used to extract tiny DNA fragments.

Researchers have now confirmed the first of two types of cholera, known as classical, was likely responsible for five of the seven devastating outbreaks in the 1800s, all of which most likely originated in waters of the Bay of Bengal.

That strain of cholera had remained a mystery because researchers were unable to examine samples from early victims. The pathogen thrives in the intestines, never reaching teeth or bones, so remnants of its DNA do not exist in skeletal remains. Despite many known cholera burials, access to historical cholera DNA had seemed impossible since it can only be found in soft-tissue remains.

... more about:
»Cholera »DNA »DNA fragment »Evolution »pandemics

But graduate student Alison Devault and evolutionary geneticists Hendrik Poinar, Brian Golding and Eddie Holmes—working with a team of other scientists—learned that a remarkable collection of tissue specimens was housed at a medical history museum. The Mütter Museum was established by the College of Physicians of Philadelphia in 1858, after the city itself was devastated by cholera earlier in the century.

Researchers carefully sampled a preserved intestine from a male victim of the 1849 pandemic and extracted information from tiny DNA fragments to reconstruct the Vibrio cholera genome.

The results, currently published in The New England Journal of Medicine, could lead to a better understanding of cholera and its modern-day strain known as El Tor, which replaced the classical strain in the 1960s for unknown reasons and is responsible for recent epidemics, including the devastating post-earthquake outbreak in Haiti.

“Understanding the evolution of an infectious disease has tremendous potential for understanding its epidemiology, how it changes over time, and what events play a role in its jump into humans,” explains Poinar, associate professor and director of the McMaster Ancient DNA Centre and an investigator with the Michael G. DeGroote Institute of Infectious Disease Research, also at McMaster University.

“We need to understand the selective pressures on the pathogen which in turn is driving its evolution, its virulence and hopefully use that information to develop better treatments,” he says. Using a sophisticated technique to extract, purify and enrich fragments of the pathogen’s DNA, the team collected precious genomic data, which answered many unresolved questions.

The researchers identified “novel genomic islands”, or genome regions that don’t occur in current strains. In addition, a well-known genic region involved in toxicity of the pathogen (a sequence called “CTX”) occurs more times in the ancient strain than in its modern descendants.

This may mean that this strain was more virulent, say researchers, but further testing will be needed.

Regarding the origins, the team’s calculations show that the classical strain and El Tor co-existed in humans and estuaries for many centuries, potentially thousands of years prior to the 19th century pandemics, and emerged as a full-blown infection in humans in the early 1800’s.

The ancestor of both the classical and El Tor strain likely circulated together in the waters of the Bay of Bengal for several thousand years before emerging in humans during what is known as the first epidemiological transition, or a time of great agricultural revolution and human settlement.

The World Health Organization estimates there are three to five million new cholera cases every year. Of those, 100,000 to 120,000 people typically die from the disease. But with access to historical collections and samples, scientists hope to gain a better understanding of how pandemics arise, spread and ultimately how they might be better controlled or stopped.

“The genomes of ancestral pathogens that have descendants today reside in these archival medical collections all over the world,” says Poinar. “We have access to hundreds of thousands of ancient specimens, which hold tremendous potential to determine the origins of past epidemics.” Thus these collections represent a treasure trove and should be carefully preserved and maintained.

The research was funded by the Natural Sciences and Engineering Research Council, the Social Sciences and Humanities Research Council, an NHMRC Australia Fellowship and an Ontario Graduate Scholarship.

Attention Editors: A full suite of multimedia material, including high def footage, high res photos and graphics is available at: https://www.dropbox.com/sh/wbs6oh726zre5og/DJmZ_ykSzU

Michelle Donovan | Newswise
Further information:
http://www.mcmaster.ca

Further reports about: Cholera DNA DNA fragment Evolution pandemics

More articles from Health and Medicine:

nachricht Using DNA origami to build nanodevices of the future
31.08.2015 | Institute for Integrated Cell-Material Sciences at Kyoto University

nachricht An ounce of prevention: Research advances on 'scourge' of transplant wards
28.08.2015 | University of Wisconsin-Madison

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: How wind sculpted Earth's largest dust deposit

China's Loess Plateau was formed by wind alternately depositing dust or removing dust over the last 2.6 million years, according to a new report from University of Arizona geoscientists. The study is the first to explain how the steep-fronted plateau formed.

China's Loess Plateau was formed by wind alternately depositing dust or removing dust over the last 2.6 million years, according to a new report from...

Im Focus: An engineered surface unsticks sticky water droplets

The leaves of the lotus flower, and other natural surfaces that repel water and dirt, have been the model for many types of engineered liquid-repelling surfaces. As slippery as these surfaces are, however, tiny water droplets still stick to them. Now, Penn State researchers have developed nano/micro-textured, highly slippery surfaces able to outperform these naturally inspired coatings, particularly when the water is a vapor or tiny droplets.

Enhancing the mobility of liquid droplets on rough surfaces could improve condensation heat transfer for power-plant heat exchangers, create more efficient...

Im Focus: Increasingly severe disturbances weaken world's temperate forests

Longer, more severe, and hotter droughts and a myriad of other threats, including diseases and more extensive and severe wildfires, are threatening to transform some of the world's temperate forests, a new study published in Science has found. Without informed management, some forests could convert to shrublands or grasslands within the coming decades.

"While we have been trying to manage for resilience of 20th century conditions, we realize now that we must prepare for transformations and attempt to ease...

Im Focus: OU astrophysicist and collaborators find supermassive black holes in quasar nearest Earth

A University of Oklahoma astrophysicist and his Chinese collaborator have found two supermassive black holes in Markarian 231, the nearest quasar to Earth, using observations from NASA's Hubble Space Telescope.

The discovery of two supermassive black holes--one larger one and a second, smaller one--are evidence of a binary black hole and suggests that supermassive...

Im Focus: What would a tsunami in the Mediterranean look like?

A team of European researchers have developed a model to simulate the impact of tsunamis generated by earthquakes and applied it to the Eastern Mediterranean. The results show how tsunami waves could hit and inundate coastal areas in southern Italy and Greece. The study is published today (27 August) in Ocean Science, an open access journal of the European Geosciences Union (EGU).

Though not as frequent as in the Pacific and Indian oceans, tsunamis also occur in the Mediterranean, mainly due to earthquakes generated when the African...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Networking conference in Heidelberg for outstanding mathematicians and computer scientists

20.08.2015 | Event News

Scientists meet in Münster for the world’s largest Chitin und Chitosan Conference

20.08.2015 | Event News

Large agribusiness management strategies

19.08.2015 | Event News

 
Latest News

Tiny Drops of Early Universe 'Perfect' Fluid

02.09.2015 | Physics and Astronomy

Learning from Nature: Genomic database standard alleviates search for novel antibiotics

02.09.2015 | Life Sciences

International research project gets high level of funding

02.09.2015 | Awards Funding

VideoLinks
B2B-VideoLinks
More VideoLinks >>>