Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Haiti cholera mutations could lead to more severe disease

16.04.2013
Strain is evolving to be more like virulent 1800s cholera

The cholera strain that transferred to Haiti in 2010 has multiple toxin gene mutations that may account for the severity of disease and is evolving to be more like an 1800s version of cholera, reports a new Northwestern Medicine study.

The strain, "altered El Tor," which emerged around 2000, is known to be more virulent and to cause more severe diarrhea and dehydration than earlier strains that had been circulating since the 1960s. This study reports the altered El Tor strain has acquired two additional signature mutations during the past decade that may further increase virulence.

In addition, these newly discovered signature mutations documented in the study further link the Haitian cholera epidemic to the strain from Nepal.

The paper will be published April 16 in the journal mBio.

The new Northwestern study suggests the strain with multi-signature toxin gene mutations may trigger a unique pattern of infection accounting for the severity of disease noted during the Haiti cholera outbreak.

"The cholera strain from the 1800s epidemic did the same thing," said Karla Satchell, the senior author of the paper and an associate professor of microbiology-immunology at Northwestern University Feinberg School of Medicine. "That strain also modified its toxin genes and the cholera got worse."

Satchell has spent her career studying a single toxin of the bacterium that causes cholera, MARTX, which helps the bacteria block the body's immune defense so cholera can colonize the gut. She closely followed genomics research conducted to track the Haiti epidemic, curious to see how her toxin was affected. She was shocked to see it had completely mutated out of existence.

"Oh, my!" she recalls thinking. "My toxin has been booted out of this key strain." She postulates that this may have affected the behavior of the mutated strain in disease.

Satchell and colleagues analyzed publicly available genomic sequencing data and found this new cholera strain had accumulated some curious genetic changes during its global spread. First, the main cholera toxin that causes the diarrhea acquired genetic changes that converted the toxin to a form similar to that produced by strains prevalent during the historic cholera epidemics of the 1800s.

Surprisingly, this new strain next acquired a genetic lesion that inactivated the MARTX toxin, previously recognized to be important for evading the immune system. A third as yet uncharacterized genetic mutation in the cholera toxin followed, suggesting a mutation emerged in the cholera toxin to compensate for the loss of MARTX.

These mutations occurring in the same strain indicate that the bacterium interacts differently with the immune system than previous strains.

"Perhaps this results in the bacterium more successfully evading early detection after a person accidently drinks cholera infected fluids," Satchell said. "Interestingly, these multiple mutations in important proteins that specifically contribute to disease could explain why this strain is causing more severe disease, although the contribution of each mutation to human infection remains to be studied."

Previously published research on the Haiti cholera strain noted the change in the bacterium's DNA and tracked its origin to Nepal, but scientists didn't ask how the changes affected the bacterium's function. In addition, scientists had believed the bacterial strains responsible for the "new wave" of cholera that engulfed Haiti and first began spreading in 2000 were functionally identical to most other strains prevalent in the environment.

Satchell's finding further confirms the strain infecting Haiti likely originated in Nepal, consistent with the conclusion from the whole genome analysis and public health studies. Strains with this unique signature of a cholera toxin with three genetic changes coupled with loss of MARTX has spread only in a very defined geographical area including India where it was first detected in 2007. It has spread through Bangladesh, Cameroon, Nepal and then into Haiti and the Dominican Republic in 2010. Even though other strains are nearly identical and barely distinguishable at the genetic level, only this very small group of isolates share this unique signature, verifying from a functional viewpoint that the strain that moved to Haiti likely originated in Nepal.

"What we discovered is that the bacterial strains responsible for the 'new wave' of cholera are not all functionally identical with minor modification as previously thought, nor are they similar to most other strains prevalent in the environment, but, in fact, the strain with multi-signature toxin gene mutations may instigate a unique pattern of infection accounting for the severity of disease noted during the Haiti cholera outbreak," Satchell said.

Marla Paul | EurekAlert!
Further information:
http://www.northwestern.edu

More articles from Health and Medicine:

nachricht Organ-on-a-chip mimics heart's biomechanical properties
23.02.2017 | Vanderbilt University

nachricht Researchers identify cause of hereditary skeletal muscle disorder
22.02.2017 | Klinikum der Universität München

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: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>