Hitting parasites where they hurt: New research shows promise in the fight against Toxoplasmosis

May 21, 2012 by James Hataway

Toxoplasmosis, a disease caused by the parasite Toxoplasma gondii, is one of the most common parasitic infections in the world. In the U.S. it is estimated that more than 22 percent of the population 12 years and older have been infected with toxoplasma, according to the Centers for Disease Control and Prevention.

Now, thanks in part to a five-year, $1.8-million grant from the National Institutes of Health, University of Georgia researcher Silvia Moreno has identified a potential target for new therapies against toxoplasma infection, which may help to protect people with compromised immune systems, developing and other sensitive populations from serious harm.

Toxoplasma works by invading healthy cells within the body, and once it has taken over, the cell's membranes protect the parasite from the . However, as it replicates and fills the cell, some parasites must venture out to find new cells to attack. It is during this process, when toxoplasma is outside the protective walls of the , that Moreno sees an opportunity to combat the parasite.

"We are interested in knowing how the parasite is able to survive long enough to find another host cell," said Moreno, professor of in the UGA Center for Tropical and Emerging Global Diseases and the Franklin College of Arts and Sciences.

Moreno's lab found that while toxoplasma is outside the protective host cell, it develops a large internal organelle called a vacuole that they think may protect the parasite and help it prepare to invade the next cell. Moreno and her collaborators call the organelle a "plant-like vacuole" because it bears resemblance to similar in plants.

"We think there are stresses the parasite encounters when it is outside, so it needs a mechanism to survive that shock," Moreno said. "At the same time, the parasite has to get ready to infect another cell; it needs to secrete proteins that will help it attach to the cell and invade."

For this vacuole to become a target, scientists must first understand the parasite's basic behaviors and biological functions. They can then start to create new therapies.

"We don't want to know how the parasite behaves just for the fun of it; we want to know where we can hit it," Moreno said. "That's the reason we study its biology because we want to know exactly where to hit toxoplasma with drugs."

Disrupting the function of the plant-like vacuole may render the parasite incapable of movement. If toxoplasma cannot safely leave the confines of a host cell, it cannot replicate and it cannot create a widespread infection.

Most people infected with toxoplasma are relatively safe from danger because the immune system is able to seek out and destroy the parasite before it causes harm.

"The parasite is very smart in that it does not kill healthy people," Moreno said. "If you are a parasite, you don't want to kill your host, because if you kill your host you're done too."

But toxoplasma can be incredibly dangerous to those with compromised immune systems, such as AIDS or chemotherapy patients, and to a fetus whose mother has been exposed to the parasite. In these situations, toxoplasma invades human cells and begins replicating, leaving behind cysts that damage brain and muscle tissue.

Moreno also said that toxoplasma serves as an excellent research and teaching tool because the plant-like vacuole may be present in the large and diverse group of animal called apicomplexans, which are the cause of several important infectious human diseases, including malaria. She said the lessons learned from toxoplasma could be useful in the treatment of these diseases.

Explore further: Mice infected with Toxoplasma gondii parasite show Alzheimer's improvements

Related Stories

Mice infected with Toxoplasma gondii parasite show Alzheimer's improvements

March 21, 2012
The parasite Toxoplasma gondii has some favorable effects on the pathogenesis and progression of a mouse model of Alzheimer's disease, reports a Mar. 21 study in the open access journal PLoS ONE.

Recommended for you

Researchers find infectious prions in Creutzfeldt-Jakob disease patient skin

November 22, 2017
Creutzfeldt-Jakob disease (CJD)—the human equivalent of mad cow disease—is caused by rogue, misfolded protein aggregates termed prions, which are infectious and cause fatal damages in the patient's brain. CJD patients ...

Surprising roles for muscle in tissue regeneration, study finds

November 22, 2017
A team of researchers at Whitehead has illuminated an important role for different subtypes of muscle cells in orchestrating the process of tissue regeneration. In a paper published in the November 22 issue of Nature, they ...

Study reveals new mechanisms of cell death in neurodegenerative disorders

November 22, 2017
Researchers at King's College London have discovered new mechanisms of cell death, which may be involved in debilitating neurodegenerative disorders, such as Alzheimer's disease and Parkinson's disease.

How rogue immune cells cross the blood-brain barrier to cause multiple sclerosis

November 21, 2017
Drug designers working on therapeutics against multiple sclerosis should focus on blocking two distinct ways rogue immune cells attack healthy neurons, according to a new study in the journal Cell Reports.

New simple test could help cystic fibrosis patients find best treatment

November 21, 2017
Several cutting-edge treatments have become available in recent years to correct the debilitating chronic lung congestion associated with cystic fibrosis. While the new drugs are life-changing for some patients, they do not ...

Researchers discover key signaling protein for muscle growth

November 20, 2017
Researchers at the University of Louisville have discovered the importance of a well-known protein, myeloid differentiation primary response gene 88 (MyD88), in the development and regeneration of muscles. Ashok Kumar, Ph.D., ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.