Featured Research

from universities, journals, and other organizations

Toxoplasmosis: The strain explains severity of infection

Date:
March 14, 2011
Source:
Johns Hopkins Medical Institutions
Summary:
Providing clues into why the severity of a common parasitic infection can vary greatly from person to person, a new study shows that each one of three strains of the cat-borne parasite Toxoplasma gondii sets off a unique reaction in the nerve cells it invades.

Robert Yolken, M.D., a neuro-virologist at Johns Hopkins Children's Center, studies the role that common viruses and parasites play in the development of psychiatric disorders.
Credit: Johns Hopkins Children's Center

Providing clues into why the severity of a common parasitic infection can vary greatly from person to person, a new Johns Hopkins study shows that each one of three strains of the cat-borne parasite Toxoplasma gondii sets off a unique reaction in the nerve cells it invades.

Past research suggests that the parasite, estimated to infect 25 percent of people worldwide, can trigger or exacerbate psychotic symptoms and schizophrenia in genetically predisposed people.

The findings of the new study, published in the March issue of the journal Infection and Immunity, help explain why the infection causes serious disease in some but not in others and clarify its role in psychiatric disorders, the researchers say.

"We already know that toxoplasmosis can play a role in some psychiatric disorders, but up until now we didn't know why. Working with human nerve cells, our study shows the exact alterations triggered by each strain that can eventually manifest themselves as symptoms," says senior investigator Robert Yolken, M.D., a neurovirologist at Johns Hopkins Children's Center.

The researchers injected human nerve cells with the three most common toxoplasma strains, each of which caused a different pattern of gene expression. One of the most basic functions in all living organisms, gene expression occurs when a gene is switched on to release a substance that tells cells what to do or not do, determining the cells' biologic behavior. Gene expression can be turned on and off, stepped up or down by various factors, including viral and bacterial invasions.

Cells infected with toxoplasma type I -- the most virulent strain in mice -- had the greatest impact on gene expression, altering more than 1,000 genes, 28 of them linked to brain development and central nervous system function and 31 others to nerve impulse and signaling.

Cells injected with the less virulent types II and III had low and moderate levels of gene expression. Infection with toxoplasma type II affected 78 genes, some of which were related to growth, certain hormones and circadian rhythm, while type III altered 344 genes, some of which were linked to metabolism.

A handful of genes were affected by all three strains, notably a gene called VIPR2 that regulates neurotransmitters and nerve signaling and may play a role in schizophrenia, the researchers say.

If these findings are confirmed in clinical studies with people, they could help physicians predict the severity of an infection by strain type and tailor treatments accordingly, the researchers say.

"While disease course in humans is often more unpredictable than what we see in the controlled setting of a lab, these results give us a fascinating first look into the distinct genetic cascade of reactions that each strain can unlock and may one day serve as the basis for individualized treatment of symptomatic infections," says lead investigator Jianchun Xiao, Ph.D., a neurovirologist at the Stanley Division of Developmental Neurovirology at Hopkins.

A 2008 study by Yolken and colleagues revealed that toxoplasma infection increases the risk for schizophrenia and could precipitate the disease in genetically predisposed people, a classic example of how genes and environment come together in the development of disease.

Most infections with toxoplasma occur early in life following exposure to the parasite from cat feces or undercooked beef or pork. Farm animals and rodents also get infected, but the parasite reaches full sexual reproduction only in cats. Infections rarely cause symptoms, but the parasite remains in the body and can reactivate after lying dormant for years.

Co-investigators on the study included Lorraine Jones-Brando, M.D., and C. Conover Talbot Jr., both of Hopkins. The research was funded by the Stanley Medical Research Institute.


Story Source:

The above story is based on materials provided by Johns Hopkins Medical Institutions. Note: Materials may be edited for content and length.


Journal Reference:

  1. J. Xiao, L. Jones-Brando, C. C. Talbot, R. H. Yolken. Differential Effects of Three Canonical Toxoplasma Strains on Gene Expression in Human Neuroepithelial Cells. Infection and Immunity, 2010; 79 (3): 1363 DOI: 10.1128/IAI.00947-10

Cite This Page:

Johns Hopkins Medical Institutions. "Toxoplasmosis: The strain explains severity of infection." ScienceDaily. ScienceDaily, 14 March 2011. <www.sciencedaily.com/releases/2011/03/110314163600.htm>.
Johns Hopkins Medical Institutions. (2011, March 14). Toxoplasmosis: The strain explains severity of infection. ScienceDaily. Retrieved October 2, 2014 from www.sciencedaily.com/releases/2011/03/110314163600.htm
Johns Hopkins Medical Institutions. "Toxoplasmosis: The strain explains severity of infection." ScienceDaily. www.sciencedaily.com/releases/2011/03/110314163600.htm (accessed October 2, 2014).

Share This



More Plants & Animals News

Thursday, October 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Attacking Superbugs

Attacking Superbugs

Ivanhoe (Oct. 1, 2014) — Two weapons hospitals can use to attack superbugs. Scientists in Ireland created a new gel resistant to superbugs, and a robot that can disinfect a room in minutes. Video provided by Ivanhoe
Powered by NewsLook.com
Cultural Learning In Wild Chimps Observed For The First Time

Cultural Learning In Wild Chimps Observed For The First Time

Newsy (Oct. 1, 2014) — Cultural transmission — the passing of knowledge from one animal to another — has been caught on camera with chimps teaching other chimps. Video provided by Newsy
Powered by NewsLook.com
Earth Has Lost Half Its Vertebrate Wildlife Since 1970: WWF

Earth Has Lost Half Its Vertebrate Wildlife Since 1970: WWF

Newsy (Sep. 30, 2014) — A new study published by the World Wide Fund for Nature found that more than half of the world's wildlife population has declined since 1970. Video provided by Newsy
Powered by NewsLook.com
Annual Dog Surfing Competition Draws California Crowds

Annual Dog Surfing Competition Draws California Crowds

AFP (Sep. 30, 2014) — The best canine surfers gathered for Huntington Beach's annual dog surfing competition, "Surf City, Surf Dog." Duration: 01:15 Video provided by AFP
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