Featured Research

from universities, journals, and other organizations

From mild-mannered to killer: Study explains plague's rapid evolution and sheds light on fighting deadly diseases

Date:
August 30, 2011
Source:
Northwestern University
Summary:
How did a bacterium that causes mild stomach irritation rapidly evolve into a deadly assassin responsible for the most devastating pandemics in human history? New DNA sequencing techniques reveal how Yersinia pseudotuberculosis became Yersinia pestis, otherwise know as the plague. The new study offers a glimpse into how the new technology might aid in the development of drugs to fight deadly diseases, including the plague.

In the evolutionary blink of an eye, a bacterium that causes mild stomach irritation evolved into a deadly assassin responsible for the most devastating pandemics in human history. How did the mild-mannered Yersinia pseudotuberculosis become Yersinia pestis, more commonly known as the Plague?

Now, scientists from Northwestern University Feinberg School of Medicine, with the use of new DNA sequencing techniques, offer long sought after evidence of how these two pathogens with virtually identical genetic matter could produce two such vastly different diseases. The Feinberg School team used the new DNA sequencing techniques to identify an unexpected source for these differences, which may help explain the Plague's rapid evolution.

The findings, to be published Aug. 29 in the journal Proceedings of the National Academy of Sciences, offer a glimpse into how the new technology might aid in the development of therapeutics to fight deadly diseases, including the Plague.

"Most people think of the Plague as a historic disease, but it's still a public health issue today, both in the human population and in animals," said Wyndham Lathem, lead author of the study and assistant professor of microbiology-immunology at Northwestern's Feinberg School. "It's extremely dangerous and highly virulent. Without treatment, it can take as little as three to five days from infection to death."

Globally, the World Health Organization reports 1,000 to 3,000 cases of Plague every year, and Y. pestis exists on every continent except Antarctica. The United States Department of Homeland Security classifies Y. pestis as a Category A biological agent, a group that also includes anthrax, smallpox and Ebola.

The Plague's ancestor, Y. pseudotuberculosis, still exists and infects humans, but it causes a mild gastrointestinal disease and most people don't show symptoms.

Lathem and colleagues have discovered the differences in disease severity between these two subspecies may have arisen from changes in small, non-coding RNAs (sRNAs), complex molecules involved in controlling many cellular processes.

The Northwestern team is the first to show that sRNAs in Yersinia affect virulence, a finding that suggests the evolution of pathogens may also occur at the level of changes in RNA and in the way protein-coding genes are regulated.

Lathem used advanced DNA sequencing technology -- called high-throughput sequencing -- to identify the complete set of sRNAs produced by Y. pseudotuberculosis. The technology enabled his team to study the diseases for the first time at a deeper genetic level.

"This technique enables us to really pick apart how pathogens evolve and how different species of bacteria are able to cause different types of disease," Lathem said. "It goes beyond looking at what proteins are produced by the bacteria. It's an additional layer of evolutionary analysis."

This detective work is important because if researchers can identify unique characteristics among deadly species such as Y. pestis, they may be able to generate new therapeutics or adapt current ones.

Unlike traditional "messenger" RNA, which is copied from DNA to create proteins and is well understood by scientists, these non-coding sRNA molecules are never translated into proteins. Hundreds of noncoding RNA molecules exist inside bacterial cells, but, until recently, scientists had not determined the function of many.

"Once we identified the complete set of sRNAs for Y. pseudotuberculosis, further analysis unlocked a number of surprising discoveries about their function," Lathem said.

Among these surprising discoveries, Lathem's team identified 150 sRNAs, a majority of which are specific to the Yersinia species, and six sRNAs unique to Y. pseudotuberculosis. Those six sRNAs are missing in Y. pestis, likely lost during its rapid evolution (somewhere between 1,500 and 20,000 years ago), and thereby potentially responsible for the Plague's virulence. Lathem's team developed this explanation because they could specify exactly which genes the sRNAs control.

First author Jovanka Koo, a postdoctoral fellow in Lathem's lab at Feinberg, noted, "An important lesson is that small changes can have big effects on sRNA functions. They can affect when an RNA is expressed or produced, the way that RNA folds, and the ability of that RNA to affect the regulated protein coding RNA." Over time, those small changes can become the difference between mild and deadly diseases.


Story Source:

The above story is based on materials provided by Northwestern University. Note: Materials may be edited for content and length.


Journal Reference:

  1. Jovanka T. Koo, Trevis M. Alleyne, Chelsea A. Schiano, Nadereh Jafari, and Wyndham W. Lathem. Global discovery of small RNAs in Yersinia pseudotuberculosis identifies Yersinia-specific small, noncoding RNAs required for virulence. Proceedings of the National Academy of Sciences, August 29, 2011 DOI: 10.1073/pnas.1101655108

Cite This Page:

Northwestern University. "From mild-mannered to killer: Study explains plague's rapid evolution and sheds light on fighting deadly diseases." ScienceDaily. ScienceDaily, 30 August 2011. <www.sciencedaily.com/releases/2011/08/110829153408.htm>.
Northwestern University. (2011, August 30). From mild-mannered to killer: Study explains plague's rapid evolution and sheds light on fighting deadly diseases. ScienceDaily. Retrieved October 23, 2014 from www.sciencedaily.com/releases/2011/08/110829153408.htm
Northwestern University. "From mild-mannered to killer: Study explains plague's rapid evolution and sheds light on fighting deadly diseases." ScienceDaily. www.sciencedaily.com/releases/2011/08/110829153408.htm (accessed October 23, 2014).

Share This



More Fossils & Ruins News

Thursday, October 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Sunken WWII U-Boat That Fired On U.S. Convoy Found

Sunken WWII U-Boat That Fired On U.S. Convoy Found

Newsy (Oct. 22, 2014) U-576, a long-lost German U-boat the U.S. sank in 1942, has been found just 30 miles off North Carolina's coast and near the wreckage of another ship. Video provided by Newsy
Powered by NewsLook.com
Turns Out Jack The Ripper's True Identity Is Still Unknown

Turns Out Jack The Ripper's True Identity Is Still Unknown

Newsy (Oct. 20, 2014) After testing DNA from a shawl found near one of Jack the Ripper's victims, a scientist said he'd identified the killer. New reports refute the claim. Video provided by Newsy
Powered by NewsLook.com
Fish Fossil Shows First-Ever Sex Was Done Side By Side

Fish Fossil Shows First-Ever Sex Was Done Side By Side

Newsy (Oct. 19, 2014) A 380-million-year-old fish may be the first creature to have copulative sex - and it was side by side with arms linked, like square dancers. Video provided by Newsy
Powered by NewsLook.com
As Sweden Hunts For Sub, "Cold War" Comparisons Flourish

As Sweden Hunts For Sub, "Cold War" Comparisons Flourish

Newsy (Oct. 19, 2014) With Sweden on the look-out for a suspected Russian sub, a lot of people are talking about the Cold War, but is it an apt comparison? Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins