Featured Research

from universities, journals, and other organizations

New promise for an HIV vaccine as researchers overcome crucial obstacle

Date:
April 2, 2013
Source:
Seattle Biomedical Research Institute (Seattle BioMed)
Summary:
For the first time, researchers were able to stimulate immune cells to produce broadly neutralizing antibodies: a critical step that has eluded researchers for decades but that provides promise for a successful HIV vaccine.

In a crucial step towards developing a successful HIV vaccine, researchers have been able, for the first time, to stimulate immune cells that can produce broadly neutralizing antibodies: a feat that has eluded vaccine researchers for decades. The exciting results are published in this month's issue of the Journal of Experimental Medicine.

It is widely accepted that a successful vaccine against HIV/AIDS would have to elicit antibodies to prevent infection from a wide spectrum of HIV strains. So far, no candidate vaccine for HIV has been able to produce such antibodies.

Leonidas Stamatatos, Andrew McGuire and their team of researchers at Seattle BioMed, in collaboration with colleagues at The Rockefeller University, the Scripps Research Institute and CalTech, wanted to understand why that was the case. A major goal of an HIV vaccine is to stimulate B cells to create antibodies that can effectively block HIV from entering a human host cell. The first generation of antibodies -- called "germline antibodies" -- are partially embedded in a B cell's membrane. If a germline antibody binds to a protein (called an "envelope protein") on the surface of HIV, even weakly, then the B cell is activated and begins producing antibodies not only on the surface of B cells, but also in the bloodstream. Activated B cells evolve to produce antibodies with even higher binding affinity to HIV, eventually resulting in a "mature" antibody. Some mature antibodies can bind to envelope proteins of many different HIV strains and prevent them from infecting cells. For this reason, these antibodies are called "broadly neutralizing antibodies." These are the antibodies a vaccine needs to elicit.

A small number of people infected with HIV naturally produce broadly neutralizing antibodies. By sequencing the DNA of their mature antibodies, Stamatatos and McGuire were able to deduce what the originating germline antibodies likely looked like. They then tested how well the mature and germline antibodies bound to the envelope protein of different HIV strains from around the world. Some of these envelope proteins have been tested previously as vaccine candidates, but they did not elicit broadly neutralizing antibodies. While the mature antibodies were able to bind 80-90% of these diverse envelope proteins, the germline antibodies did not bind at all. This indicated that a problem with previously tested HIV vaccines is that they do not bind to germline antibodies on B cells that ultimately give rise to mature, broadly neutralizing antibodies. Without this first binding step, the immune response to HIV is stopped before it can even truly begin.

Next, they turned to the structure of the HIV envelope proteins to determine why they were able to bind to the mature antibodies but not the germline. They discovered that several sugar molecules, called glycans, which HIV adds to its envelope protein to evade the immune system, were blocking the germline antibody from binding to and activating B cells.

After engineering an HIV envelope protein that lacks specific glycans, McGuire and Stamatatos ran their binding tests again. This time, the germline antibodies were able to bind the modified HIV protein. They also verified that the modified HIV protein was capable of starting the process of antibody maturation in B cells, kicking off an immune response that could eventually result in broadly neutralizing antibodies.

"We have overcome the first obstacle to elicit one type of anti-HIV broadly neutralizing antibodies through vaccination," explains McGuire. By administering the modified HIV protein as a vaccine, the immune system could become equipped to combat the real virus when it is encountered years down the line.


Story Source:

The above story is based on materials provided by Seattle Biomedical Research Institute (Seattle BioMed). Note: Materials may be edited for content and length.


Cite This Page:

Seattle Biomedical Research Institute (Seattle BioMed). "New promise for an HIV vaccine as researchers overcome crucial obstacle." ScienceDaily. ScienceDaily, 2 April 2013. <www.sciencedaily.com/releases/2013/04/130402090836.htm>.
Seattle Biomedical Research Institute (Seattle BioMed). (2013, April 2). New promise for an HIV vaccine as researchers overcome crucial obstacle. ScienceDaily. Retrieved September 14, 2014 from www.sciencedaily.com/releases/2013/04/130402090836.htm
Seattle Biomedical Research Institute (Seattle BioMed). "New promise for an HIV vaccine as researchers overcome crucial obstacle." ScienceDaily. www.sciencedaily.com/releases/2013/04/130402090836.htm (accessed September 14, 2014).

Share This



More Health & Medicine News

Sunday, September 14, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Respiratory Virus Spreads To Northeast, Now In 21 States

Respiratory Virus Spreads To Northeast, Now In 21 States

Newsy (Sep. 14, 2014) The respiratory virus Enterovirus D68, which targets children, has spread from the Midwest to 21 states. Video provided by Newsy
Powered by NewsLook.com
Shocker: Journalists Are Utterly Addicted To Coffee

Shocker: Journalists Are Utterly Addicted To Coffee

Newsy (Sep. 13, 2014) A U.K. survey found that journalists consumed the most amount of coffee, but that's only the tip of the coffee-related statistics iceberg. Video provided by Newsy
Powered by NewsLook.com
Contagious Respiratory Illness Continues to Spread Across U.S.

Contagious Respiratory Illness Continues to Spread Across U.S.

Reuters - US Online Video (Sep. 12, 2014) Hundreds of children in several states have been stricken by a serious respiratory illness that is spreading across the U.S. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Ebola Batters Sierra Leone Economy Too

Ebola Batters Sierra Leone Economy Too

Reuters - Business Video Online (Sep. 12, 2014) The World Health Organisation warns that local health workers in West Africa can't keep up with Ebola - and among those countries hardest hit by the outbreak, the economic damage is coming into focus, too. As David Pollard reports, Sierra Leone admits that growth in one of the poorest economies in the region is taking a beating. Video provided by Reuters
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