Featured Research

from universities, journals, and other organizations

Immune Exhaustion Driven By Antigen In Chronic Viral Infection

Date:
May 18, 2009
Source:
Emory University
Summary:
During a chronic viral infection, exhaustion depletes the ability of immune cells to respond to the infecting virus. Exhaustion occurs when large amounts of virus, or pieces of the virus (known as antigens), are seen by cells of the immune system over a prolonged period.

A main reason why viruses such as HIV or hepatitis C persist despite a vigorous initial immune response is exhaustion. The T cells, or white blood cells, fighting a chronic infection eventually wear out.

Researchers at Emory Vaccine Center have demonstrated that exhaustion is driven by how the immune system detects infecting viruses.

To recognize the presence of a viral infection, T cells must be presented with bits of viral protein in a molecular frame supplied by other cells in the body -- called MHC (major histocompatibility complex) class I molecules.

In mice infected by lymphocytic choriomeningitis virus (LCMV), T cells became more or less exhausted depending on how much properly framed viral protein was available.

Insights from the research could guide efforts to revive the immune system in people with chronic viral infections. The results are published online this week in the Proceedings of the National Academy of Sciences.

Working with Vaccine Center director Rafi Ahmed, PhD, postdoctoral fellow Scott Mueller, PhD, examined the effects of limiting what kind of cells could display the viral antigens.

Ahmed is professor of microbiology and immunology at Emory University School of Medicine and a Georgia Research Alliance Eminent Scholar.

By performing bone marrow transplants on genetically engineered mice, Mueller created mice with MHC class I molecules on blood and immune system cells but missing from other cells such as nerve cells and connective tissue. LCMV infects both cells that come from bone marrow and cells that don't. But the roles each type of cell plays in communicating the infection to the immune system is different.

"We were trying to sort out which of several factors contribute to T cell exhaustion, such as viral antigen, inflammation and where the immune system encounters the virus," Mueller says. "What came out of these experiments allowed us to answer a broad question: the role of antigen in driving exhaustion."

When injected with LCMV, the altered mice had more energetic and responsive T cells early during the infection. But later, the altered mice had much higher levels of virus and more exhausted T cells. This contrast demonstrates how the level of antigen present is the motor behind immune exhaustion during the chronic infection.

"Early on, the T cells were healthier because they saw less antigen, and only saw it on cells that came from bone marrow," Mueller says. "But later, the immune system had trouble getting rid of the virus because the T cells couldn't recognize infection in cells that were not able to present the viral antigens."

The research was supported by the National Institutes of Health and the Gates Foundation.


Story Source:

The above story is based on materials provided by Emory University. Note: Materials may be edited for content and length.


Cite This Page:

Emory University. "Immune Exhaustion Driven By Antigen In Chronic Viral Infection." ScienceDaily. ScienceDaily, 18 May 2009. <www.sciencedaily.com/releases/2009/05/090513173459.htm>.
Emory University. (2009, May 18). Immune Exhaustion Driven By Antigen In Chronic Viral Infection. ScienceDaily. Retrieved October 20, 2014 from www.sciencedaily.com/releases/2009/05/090513173459.htm
Emory University. "Immune Exhaustion Driven By Antigen In Chronic Viral Infection." ScienceDaily. www.sciencedaily.com/releases/2009/05/090513173459.htm (accessed October 20, 2014).

Share This



More Health & Medicine News

Monday, October 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

How Nigeria Beat Its Ebola Outbreak

How Nigeria Beat Its Ebola Outbreak

Newsy (Oct. 20, 2014) The World Health Organization has declared Nigeria free of Ebola. Health experts credit a bit of luck and the government's initial response. Video provided by Newsy
Powered by NewsLook.com
Another Study Suggests Viagra Is Good For The Heart

Another Study Suggests Viagra Is Good For The Heart

Newsy (Oct. 20, 2014) An ingredient in erectile-dysfunction medications such as Viagra could improve heart function. Perhaps not surprising, given Viagra's history. Video provided by Newsy
Powered by NewsLook.com
Ebola Worries End for Dozens on U.S. Watch Lists

Ebola Worries End for Dozens on U.S. Watch Lists

Reuters - US Online Video (Oct. 20, 2014) Forty-three people who had contact with Thomas Eric Duncan, the first person diagnosed with Ebola in the U.S., were cleared overnight of twice-daily monitoring after 21 days of showing no symptoms. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Beijing Marathon Runners Brave Hazardous Air Pollution

Beijing Marathon Runners Brave Hazardous Air Pollution

AFP (Oct. 19, 2014) Tens of thousands of runners battled thick smog at the Beijing Marathon on Sunday, with some donning masks as the levels of PM2.5 small pollutant particles soared to 16 times the maximum recommended level. Duration: 00:54 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


Health & Medicine

Mind & Brain

Living & Well

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