Featured Research

from universities, journals, and other organizations

HIV Handicaps Itself To Escape Immune System Pressure

Date:
April 16, 2009
Source:
Emory University
Summary:
HIV quickly mutates and evolves in response to pressure from the immune system. A set of three mutations that conceal HIV from particularly strong human immune systems slow viral replication considerably. However, once all three mutations are in place, the virus becomes "invisible" to the immune system and its abundance shoots upwards. The results demonstrate the importance of "killer" T cell immune responses in controlling HIV and shows that vaccines will need to stimulate responses against several parts of the virus.

People with the ability to stave off AIDS for years after initial infection by HIV have been called "long-term non-progressors" or "elite controllers."

One component of this remarkable resistance comes from an individual's HLA genes. Long-term non-progressors tend to have HLA genes that help the immune system recognize and fight HIV more efficiently.

A team of researchers from the Emory Vaccine Center studying HIV-infected people with particularly effective HLA genes has observed how the virus mutates and evolves in response to immune pressure.

The observations, published in the Journal of Experimental Medicine, can provide guidance on what kinds of immune responses a successful HIV vaccine should generate.

The team was led by Eric Hunter, PhD, professor of pathology and laboratory medicine at Emory University School of Medicine, Emory Vaccine Center, and Yerkes National Primate Research Center. Hunter is a Georgia Research Alliance Eminent Scholar. First author Hayley Crawford, a graduate student at Oxford University, England, performed much of the research while working in Hunter's laboratory.

The Emory/Oxford team studied people in Zambia and South Africa with one form of the HLA gene that helps the immune system control HIV, called HLA-B*5703.

HLA genes encode molecules that display fragments of viral proteins, known as epitopes, on the surface of infected cells. When white blood cells known as cytotoxic T lymphocytes (CTLs) spot certain combinations of HLA molecules and viral epitopes, they attack the infected cells.

The authors show that a set of three mutations in HIV's Gag protein, which makes up the viral core, progressively slow viral replication. In cell culture, a triple-mutant virus replicates 20 times slower than normal. However, these same mutations effectively eliminate the ability of CTLs to detect the virus. so that in an infected person, once all three mutations are in place, viral abundance shoots upwards.

"In this situation, HIV resembles a thief picking a lock. Once all three mutations are in place, the lock is picked and the virus can thrive because the immune system can't fight against it," Hunter says.

The team followed the mutations' fate after transmission by studying couples in which one person had infected the other. If the recipient lacked HLA-B*5703, the virus lost the mutations, because the three handicapping mutations were not useful in evading the new, different immune system. But unlucky recipients with HLA-B*5703 who got the triple-mutant virus from their partners quickly got sick.

The results demonstrate the importance of CTLs, the white blood cells that attack viral infected cells, in controlling HIV infection. They also suggest that a successful vaccine will need to induce responses to many epitopes, or combinations of HLA molecule and viral protein.


Story Source:

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


Journal Reference:

  1. Crawford et al. Evolution of HLA-B*5703 HIV-1 escape mutations in HLA-B*5703-positive individuals and their transmission recipients. Journal of Experimental Medicine, Vol. 206 No. 4 909-921 2009; DOI: 10.1084/jem.20081984

Cite This Page:

Emory University. "HIV Handicaps Itself To Escape Immune System Pressure." ScienceDaily. ScienceDaily, 16 April 2009. <www.sciencedaily.com/releases/2009/04/090413083307.htm>.
Emory University. (2009, April 16). HIV Handicaps Itself To Escape Immune System Pressure. ScienceDaily. Retrieved April 19, 2014 from www.sciencedaily.com/releases/2009/04/090413083307.htm
Emory University. "HIV Handicaps Itself To Escape Immune System Pressure." ScienceDaily. www.sciencedaily.com/releases/2009/04/090413083307.htm (accessed April 19, 2014).

Share This



More Health & Medicine News

Saturday, April 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Nine-Month-Old Baby Can't Open His Mouth

Nine-Month-Old Baby Can't Open His Mouth

Newsy (Apr. 19, 2014) Nine-month-old Wyatt Scott was born with a rare disorder called congenital trismus, which prevents him from opening his mouth. Video provided by Newsy
Powered by NewsLook.com
'Holy Grail' Of Weight Loss? New Find Could Be It

'Holy Grail' Of Weight Loss? New Find Could Be It

Newsy (Apr. 18, 2014) In a potential breakthrough for future obesity treatments, scientists have used MRI scans to pinpoint brown fat in a living adult for the first time. Video provided by Newsy
Powered by NewsLook.com
Little Progress Made In Fighting Food Poisoning, CDC Says

Little Progress Made In Fighting Food Poisoning, CDC Says

Newsy (Apr. 18, 2014) A new report shows rates of two foodborne infections increased in the U.S. in recent years, while salmonella actually dropped 9 percent. Video provided by Newsy
Powered by NewsLook.com
Scientists Create Stem Cells From Adult Skin Cells

Scientists Create Stem Cells From Adult Skin Cells

Newsy (Apr. 17, 2014) The breakthrough could mean a cure for some serious diseases and even the possibility of human cloning, but it's all still a way off. 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