Featured Research

from universities, journals, and other organizations

HIV vaccine failure probably caused by virus used, says new research

Date:
November 19, 2009
Source:
Imperial College London
Summary:
The recent failure of an HIV vaccine was probably caused by the immune system reacting to the virus 'shell' used to transmit the therapy around the body, according to new research. The researchers behind the study say their findings mean scientists may have to rethink other vaccines they are developing for diseases like HIV, tuberculosis and malaria, which are delivered in the same way, using the same virus "shell."

The recent failure of an HIV vaccine was probably caused by the immune system reacting to the virus 'shell' used to transmit the therapy around the body, according to research published in the Proceedings of the National Academy of Sciences.

The trial, called 'STEP', was halted in September 2007 because preliminary results suggested that people who had been given the vaccine were more likely to be infected with HIV than people who had been given a placebo.

The researchers behind the study, from Imperial College London, King's College London and Royal Holloway, University of London, say their findings mean scientists may have to rethink other vaccines they are developing for diseases like HIV, tuberculosis and malaria, which are delivered in the same way, using the same virus 'shell'.

The vaccine used an adenovirus, which normally causes the common cold, to enable the vaccine therapy to travel around the body. Harmless HIV genes were then inserted into the virus. It was thought that this would help the immune system to learn to recognise and fight off HIV.

The new study suggests that after receiving the trial vaccination, people who had previously built up immunity to the adenovirus had an influx of immune cells called CD4 T-cells homing in on their mucous membranes, as these cells prepared to fight off a new adenovirus infection. Mucous membranes are found in areas including the nose, mouth, vagina and gut. HIV naturally infects CD4 T-cells, so this inadvertently provided HIV with an abundance of potential new homes at the sites where the virus would naturally enter the body during sexual intercourse, thereby increasing people's risk of infection.

The researchers say their findings are a warning for scientists developing adenovirus vaccines against other diseases, as the same effect occurs with other, perhaps all, adenovirus subtypes.

Adenovirus infection is common and there are 51 known human strains. Around half of all adults in the developed world and about 90 percent of individuals in sub-Saharan Africa, where HIV is most prevalent, have built up immunity to the subtype of adenovirus used in STEP.

Preliminary results of the vaccine trial showed that people who had previously been infected with the adenovirus used in the trial had a significantly higher risk of being infected with HIV following the vaccine compared to people who were given a placebo.

Dr Steven Patterson, who is the corresponding author of the study from the Division of Investigative Science at Imperial College London, said: "HIV is a huge threat to global health, with 2.7 million people becoming infected every year. We were all hopeful that the STEP trial would be a success, so when the researchers published their results and the trial was halted, we were all very surprised and disappointed. Scientists use adenoviruses in all sorts of vaccines and we did not expect this result. It was vital to discover what caused this increase in HIV infection risk so we could avoid the same problem in future trials.

"Our research suggests that the adenovirus-based HIV vaccine effectively instructs the cells that HIV infects to gather round exactly where HIV is likely to be introduced. This is clearly worrying for this kind of vaccine. Scientists are currently developing adenovirus-based vaccines to protect people against TB and malaria as well as HIV, but they may have to rethink these vaccines if the effect we describe in our new paper is a problem for all of them," added Dr Patterson.

The researchers measured antibodies against adenovirus type 5 (Ad-5) and adenovirus type 11 (Ad-11) in 20 healthy volunteers to determine who had been infected. They then took samples of the volunteers' immune cells and grew them in the laboratory to see whether their CD4 cells would recognise Ad-5 and Ad-11. When the researchers added adenoviruses to the tissue cultures, they found that the viruses activated the CD4 cells and caused them to grow and replicate. They found that the newly generated CD4 cells had particular kinds of molecules on their surface that enabled them to migrate to mucosal membranes.

The results also showed that CD4 cells can recognise and react to another distinct subtype of adenovirus, regardless of which subtype the person was infected with initially. The authors say this means all subtypes of adenovirus are likely to be unsuitable in HIV vaccines.


Story Source:

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


Journal Reference:

  1. Adel Benlahrech, Julian Harris, Andrea Meiser, Timos Papagatsias, Julia Hornig, Peter Hayes, Andre Lieber, Takis Athanasopoulos, Veronique Bachy, Eszter Csomor, Rod Daniels, Kerry Fisher, Frances Gotch, Len Seymour, Karen Logan, Romina Barbagallo, Linda Klavinskis, George Dickson, and Steven Patterson. Adenovirus vector vaccination induces expansion of memory CD4 T cells with a mucosal homing phenotype that are readily susceptible to HIV-1. Proceedings of the National Academy of Sciences, 2009; DOI: 10.1073/pnas.0907898106

Cite This Page:

Imperial College London. "HIV vaccine failure probably caused by virus used, says new research." ScienceDaily. ScienceDaily, 19 November 2009. <www.sciencedaily.com/releases/2009/11/091116165635.htm>.
Imperial College London. (2009, November 19). HIV vaccine failure probably caused by virus used, says new research. ScienceDaily. Retrieved September 2, 2014 from www.sciencedaily.com/releases/2009/11/091116165635.htm
Imperial College London. "HIV vaccine failure probably caused by virus used, says new research." ScienceDaily. www.sciencedaily.com/releases/2009/11/091116165635.htm (accessed September 2, 2014).

Share This




More Health & Medicine News

Tuesday, September 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Get on Your Bike! London Cycling Popularity Soars Despite Danger

Get on Your Bike! London Cycling Popularity Soars Despite Danger

AFP (Sep. 1, 2014) Wedged between buses, lorries and cars, cycling in London isn't for the faint hearted. Nevertheless the number of people choosing to bike in the British capital has doubled over the past 15 years. Duration: 02:27 Video provided by AFP
Powered by NewsLook.com
Can You Train Your Brain To Eat Healthy?

Can You Train Your Brain To Eat Healthy?

Newsy (Sep. 1, 2014) New research says if you condition yourself to eat healthy foods, eventually you'll crave them instead of junk food. Video provided by Newsy
Powered by NewsLook.com
We've Got Mites Living In Our Faces And So Do You

We've Got Mites Living In Our Faces And So Do You

Newsy (Aug. 30, 2014) A new study suggests 100 percent of adult humans (those over 18 years of age) have Demodex mites living in their faces. Video provided by Newsy
Powered by NewsLook.com
Liberia Continues Fight Against Ebola

Liberia Continues Fight Against Ebola

AFP (Aug. 30, 2014) Authorities in Liberia try to stem the spread of the Ebola epidemic by raising awareness and setting up sanitation units for people to wash their hands. Duration: 00:41 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:
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