Featured Research

from universities, journals, and other organizations

Bacterial Protein Shows Promise In Treating Intestinal Parasites

Date:
September 29, 2006
Source:
University of California - San Diego
Summary:
Scientists at the University of California, San Diego and Yale University have discovered that a natural protein produced by Bacillus thuringiensis, a bacterium sprayed on crops by organic farmers to reduce insect damage, is highly effective at treating hookworm infections in laboratory animals.

Adult hookworm attached to intestine.
Credit: Richard Bungiro, Yale

Scientists at the University of California, San Diego and Yale University have discovered that a natural protein produced by Bacillus thuringiensis, a bacterium sprayed on crops by organic farmers to reduce insect damage, is highly effective at treating hookworm infections in laboratory animals.

Their discovery, detailed in this week’s early online edition of the Proceedings of the National Academy of Sciences, could pave the way for the development of more effective treatments for hookworm and other soil-transmitted nematode infections, which are a major global health problem in developing countries. Many of the nearly two billion people worldwide infected with these intestinal parasites are children, who are at particular risk for anemia, malnutrition and delayed growth.

The UCSD-Yale team found that a protein produced by the bacterium Bacillus thuringiensis, or Bt, given orally to laboratory hamsters infected with hookworms was as effective in eliminating the parasites, curing anemia and restoring weight gain in the hamsters as mebendazole, one of the drugs currently recommended to treat infections in humans. The scientists also discovered that this protein, called Cry5B, targets both developing, or larval, stages and adult parasites, as well as impairs the excretion of eggs by female worms.

Hookworms cause anemia by attaching to the intestine and feeding on their host’s blood and nutrients, causing anemia and weight loss. The researchers said in their paper that because this naturally-produced protein is safe to humans and other vertebrates and can be produced inexpensively in large quantities, it has the potential to substantially improve this global health problem.

“Our ability to control parasitic nematode infections with chemotherapy on a global scale is dependent on the availability of medicines that are safe, effective, and inexpensive to manufacture,” said Michael Cappello, one of two principal authors of the study and a professor of pediatrics and epidemiology & public health at Yale School of Medicine. “We believe that Bt crystal proteins not only meet, but exceed these essential criteria.”

The discovery is particularly relevant to global health, because of concerns about the potential emergence of resistance in human intestinal nematodes to currently available medicines.

“There are only a few new agents under development for the treatment of hookworm and other intestinal parasite infections," said Raffi Aroian, an associate professor of biology at UCSD and co-principal author of the study. " Crystal toxins are safe to humans, mammals and other vertebrates. And it might be possible to improve the efficacy of current treatments by giving a drug like mebendazole and Cry5B simultaneously.”

Other authors of the study are Richard Bungiro and Lisa Harrison of the Yale medical school and Larry Bischof, Joel Griffitts and Brad Barrows of UCSD.

Aroian and his UCSD colleagues discovered five years ago that the roundworm C. elegans and other nematodes are susceptible to the effects of Cry5B, then known primarily as an insecticide. The toxin forms tiny holes in the membranes of the cells of nematodes and insects. However, since the toxin can’t bind to the cells of mammals or other vertebrates, Cry proteins can’t hurt humans.

“Crystal proteins had been used for decades to kill insects by organic farmers who sprayed their crops with Bt,” said Aroian. “Until now, however, no one has used a purified Cry protein to treat a parasitic nematode.”

Aroian met Cappello, a pediatric infectious diseases specialist who studies hookworm, at a meeting of the Burroughs-Wellcome Fund and decided to collaborate on a project to see if crystal proteins could be effective against hookworm infections. Three years ago, Aroian and his colleagues purified Cry5B toxin and sent it to Cappello, who then tested the compound in a laboratory model of hookworm infection.

“It worked on the first day,” said Aroian. “Laboratory animals treated with Cry5B survived a lethal hookworm infection, and showed no side effects from the medication.”

Colleagues in Cappello’s lab then carried out additional experiments that demonstrated that Cry5B was comparable to mebendazole for treating hookworm infection in laboratory animals. Additional studies also determined which life cycle stages of the parasite were most susceptible to Cry5B and at what concentrations.

“These experiments confirmed that the mechanism of action of Cry5B in Ancylostoma hookworms appears to be identical to that for other nematodes, including C. elegans,” said Cappello. “This suggests that crystal proteins will likely have activity against a broad range of nematodes, and could be used to treat children who are often infected with multiple intestinal parasites. Studies are underway to fully define the spectrum of activity of Cry5B as part of its preclinical development as a human therapeutic.”

The study was supported by grants from the National Institutes of Health and the Burroughs Wellcome Fund.


Story Source:

The above story is based on materials provided by University of California - San Diego. Note: Materials may be edited for content and length.


Cite This Page:

University of California - San Diego. "Bacterial Protein Shows Promise In Treating Intestinal Parasites." ScienceDaily. ScienceDaily, 29 September 2006. <www.sciencedaily.com/releases/2006/09/060925143158.htm>.
University of California - San Diego. (2006, September 29). Bacterial Protein Shows Promise In Treating Intestinal Parasites. ScienceDaily. Retrieved July 25, 2014 from www.sciencedaily.com/releases/2006/09/060925143158.htm
University of California - San Diego. "Bacterial Protein Shows Promise In Treating Intestinal Parasites." ScienceDaily. www.sciencedaily.com/releases/2006/09/060925143158.htm (accessed July 25, 2014).

Share This




More Health & Medicine News

Friday, July 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

New Painkiller Designed To Discourage Abuse: Will It Work?

New Painkiller Designed To Discourage Abuse: Will It Work?

Newsy (July 24, 2014) The FDA approved Targiniq ER on Wednesday, a painkiller designed to keep users from abusing it. Like any new medication, however, it has doubters. Video provided by Newsy
Powered by NewsLook.com
Doctor At Forefront Of Fighting Ebola Outbreak Gets Ebola

Doctor At Forefront Of Fighting Ebola Outbreak Gets Ebola

Newsy (July 24, 2014) Sheik Umar Khan has treated many of the people infected in the Ebola outbreak, and now he's become one of them. Video provided by Newsy
Powered by NewsLook.com
Condemned Man's US Execution Takes Nearly Two Hours

Condemned Man's US Execution Takes Nearly Two Hours

AFP (July 24, 2014) America's death penalty debate raged Thursday after it took nearly two hours for Arizona to execute a prisoner who lost a Supreme Court battle challenging the experimental lethal drug cocktail. Duration: 00:55 Video provided by AFP
Powered by NewsLook.com
Can Watching TV Make You Feel Like A Failure?

Can Watching TV Make You Feel Like A Failure?

Newsy (July 24, 2014) A study by German researchers claims watching TV while you're stressed out can make you feel guilty and like a failure. 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:
from the past week

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