Free Newsletters - Space News - Defense Alert - Environment Report - Energy Monitor
. Earth Science News .




EPIDEMICS
50-year cholera mystery solved
by Staff Writers
Austin TX (SPX) Jun 07, 2012


File image courtesy AFP.

For 50 years scientists have been unsure how the bacteria that gives humans cholera manages to resist one of our basic innate immune responses. That mystery has now been solved, thanks to research from biologists at The University of Texas at Austin.

The answers may help clear the way for a new class of antibiotics that don't directly shut down pathogenic bacteria such as V. cholerae, but instead disable their defenses so that our own immune systems can do the killing.

Every year cholera afflicts millions of people and kills hundreds of thousands, predominantly in the developing world. The infection causes profuse diarrhea and vomiting. Death comes from severe dehydration.

"If you understand the mechanism, the bacterial target, you're more likely to be able to design an effective antibiotic," says Stephen Trent, associate professor of molecular genetics and microbiology and lead researcher on the study.

The bacterium's defense, which was unmasked this month in the Proceedings of the National Academy of Sciences, involves attaching one or two small amino acids to the large molecules, known as endotoxins, that cover about 75 percent of the bacterium's outer surface.

"It's like it's hardening its armor so that our defenses can't get through," says Trent.

Trent says these tiny amino acids simply change the electrical charge on that outer surface of the bacteria. It goes from negative to neutral.

That's important because the molecules we rely on to fight off such bacteria, which are called cationic antimicrobial peptides (CAMPs), are positively charged. They can bind to the negatively charged surface of bacteria, and when they do so, they insert themselves into the bacterial membrane and form a pore. Water then flows through the pore into the bacterium and pops it open from the inside, killing the harmful bacteria.

It's an effective defense, which is why these CAMPs are ubiquitous in nature (as well as one of the main ingredients in over-the-counter antibacterial ointments such as Neosporin).

However, when the positively charged CAMPs come up against the neutral V. cholerae bacteria, they can't bind. They bounce away, and we're left vulnerable.

V. cholerae can then invade our intestines and turn them into a kind of factory for producing more cholera, in the process rendering us incapable of holding onto fluids or extracting sufficient nutrients from what we eat and drink.

"It pretty much takes over your normal flora," says Trent.

Trent says that scientists have known for some time that the strain of V. cholerae responsible for the current pandemic in Haiti and elsewhere is resistant to these CAMPs. It's that resistance that is likely responsible, in part, for why the current strain displaced the strain that was responsible for previous pandemics.

"It's orders of magnitude more resistant," says Trent.

Now that Trent and his colleagues understand the mechanism behind this resistance, they hope to use that knowledge to help develop antibiotics that can disable the defense, perhaps by preventing the cholera bacteria from hardening their armor. If that happened, our CAMPs could do the rest of the work.

Trent says the benefits of such an antibiotic would be considerable. It might be effective against not just cholera but a range of dangerous bacteria that use similar defenses. And because it disarms but doesn't kill the bacteria outright, as traditional antibiotics do, it might take longer for the bacteria to mutate and evolve resistance in response to it.

"If we can go directly at these amino acids that it uses to protect against us, and then allow our own innate immune system to kill the bug, there could be less selection pressure," he says.

Trent's lab is now screening for compounds that would do precisely that.

.


Related Links
University of Texas at Austin
Epidemics on Earth - Bird Flu, HIV/AIDS, Ebola






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





EPIDEMICS
China faces 'serious' epidemic of drug-resistant TB
Washington (AFP) June 6, 2012
China faces a "serious epidemic" of drug-resistant tuberculosis according to the first-ever nationwide estimate of the size of the problem there, said a US-published study on Wednesday. "In 2007, one third of the patients with new cases of tuberculosis and one half of the patients with previously treated tuberculosis had drug-resistant disease," said the study in the New England Journal of M ... read more


EPIDEMICS
Japan agency sorry for comparing radiation to wife

Lithuania launches regional nuclear safety watchdog

Italy's quake-struck north tries to reassure tourists

Ferrari auction to raise money for Italy quake

EPIDEMICS
Samsung vows US launch of Galaxy despite Apple suit

Repelling the drop on top

Elvis Lives! US firm to create 'virtual' Presley

Taiwan's HTC denies Microsoft snub over Windows 8

EPIDEMICS
Practical Tool Can 'Take Pulse' Of Blue-Green Algae Status In Lakes

Grazing snails rule the waves

New world, new worries as Brazil dam changes Amazon

Ethiopian dam spurs debate

EPIDEMICS
Expedition studies acid impacts on Arctic

Huge algae blooms discovered beneath Arctic ice

Peru needs glacier loss monitoring: dire UN warning

Greenland's current loss of ice mass

EPIDEMICS
Scientists complete most comprehensive genetic analysis yet of corn

EU farming reform caught in budget stalemate

France to ban Swiss pesticide as bee threat

Brazil farmers in legal feud with Monsanto over GM soy

EPIDEMICS
Huge dock washed up on US coast, thought from Japan

Huge Japan tsunami dock washes up on US beach

Powerful 6.0 quake strikes southern Peru

Hurricane season is here, and FSU scientists predict an active one

EPIDEMICS
LRA rebels attack DR Congo wildlife park guards

Conflicts hinder Niger, Mali locust control: UN food agency

Somali soldiers train for urban combat in rural Uganda

Sierra Leone's gruesome civil war

EPIDEMICS
Fossil discovery sheds new light on evolutionary history of higher primates

Monkey lip smacks provide new insights into the evolution of human speech

Stanford psychologists aim to help computers understand you better

New Mini-sensor Measures Magnetic Field of the Brain




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement