Key Protein in Attack of AIDS Virus Discovered
A protein that plays a key role in the deadly attack of the AIDS virus has been discovered by federal scientists, ending a decade-long search by worldwide research laboratories.
A group at the National Institute of Allergy and Infectious Diseases identified the protein, which it calls fusin, that must be present for the human immunodeficiency virus to infect white blood cells, the primary target of the virus.
Other experts said the discovery is “very significant” and eventually could lead to new drugs and vaccines to combat the lethal infection by HIV, which causes AIDS.
A report on the finding is to be published today in the journal Science.
Edward A. Berger, leader of the NIAID team that made the discovery, said the finding is basic research at a molecular level about HIV and will have no immediate impact on people infected with the disease. But the discovery answers a question that has confounded researchers for 10 years and slowed the search for a cure.
HIV attacks cells in the bloodstream that have on their surface a molecule called CD4. This molecule acts as a receptor that the HIV particle uses to fuse with the target cell. But researchers discovered that CD4, by itself, was not enough. Some other receptor on the cell surface had to be present for the HIV infection to occur.
That second receptor, said Berger, is fusin.
“The discovery gives us a major new insight into how HIV gets into cells and suggests some things we weren’t even considering about how HIV causes disease,” Berger said.
“This is very significant basic research that helps to solve the puzzle of how HIV gets into cells,” said John Moore, a researcher at the Aaron Diamond AIDS Research Center in New York. “There has been very intensive efforts by many labs to find this. Many people have given up.
“It was like looking for the unicorn--we weren’t really sure it was there,” Moore said.
Robert Gallo of the University of Maryland, the co-discoverer of the virus, said the research “is a very important paper.”
“This is one of the milestones in AIDS research,” he said. “This opens new doors for therapy and for developing vaccines.”
Berger and his colleagues found fusin by genetically altering a laboratory virus, called vaccinia, to resemble HIV and to cause a cell to turn blue if it fuses with the virus.
They then exposed this laboratory virus to cultured mouse cells that had been altered to include the human CD4 gene, along with selected genes for other molecules found on the surface of human cells.
Through a painstaking process of elimination, the researchers eventually isolated fusin and identified it as the protein that is a co-factor with CD4 in the HIV infection process.
To prove the role of fusin, CD4 cells with and without fusin were exposed to HIV from blood samples. Only the cells with fusin became infected. The researchers then developed an antibody against fusin and found that laboratory cultures protected by the antibody could not be infected by HIV.
