Washington, June 26 (Reuters): Researchers said today they had figured out how a rare antibody sees past the disguises of the AIDS virus — a finding that may lead to a vaccine that will finally work against the killer microbe.
The antibody, taken from an unusual patient whose body can resist the virus, recognises and attacks the human immunodeficiency virus, unlike most of the body’s defences. “Nothing like this has been seen before,” Ian Wilson of The Scripps Research Institute in La Jolla, California, who led the research, said in a statement. AIDS has killed 25 million people around the world and is projected to kill 80 million by 2010. The only real hope of fighting the incurable virus is a vaccine, but efforts so far have flopped although dozens of vaccines are being tested.
Antibodies are an important arm of the body’s defences against germs. They are usually able to recognise an invader by structures on its surface, called antigens, and can either call in help, or neutralise it themselves by pasting themselves against it.
Most vaccines in use today stimulate the production of neutralising antibodies. The human body makes plenty of antibodies against HIV, but the virus disguises itself with human sugars.
One antibody seems to be able to see past this ruse. Called 2G12, it was found by Austrian researchers in a patient who seemed to resist acquired immune deficiency syndrome — the condition caused as HIV destroys the immune system over time. Writing in the journal Science, Wilson and colleagues said they had figured out how 2G12 does it.
It recognises that while HIV is covered up with human sugars, they are not arranged in a human-like way. The antibody does this with a special structure of its own, which Wilson and colleagues, including a team at Oxford University in Britain, have crystallised and imaged.
“The Fab (antigen recognition) arms are interlocked,” said Scripps researcher Dennis Burton, who worked on the study. “That is a unique arrangement, and it is good for recognising a cluster of shapes like sugars on a virus.”
Now what needs to be done is to use the structure of the antibody as a template to design an antigen to stimulate the production of 2G12 or another antibody that will neutralize HIV, the researchers said.
The approach might also work for making vaccines against other germs, said Wilson.“Can we now use this to engineer antibodies with higher affinity against other antigens or clusters of antigens'” he asked.