Researchers studying people who are resistant to HIV have found a group of natural proteins that seem to inhibit the progressive infection of the virus that causes Aids, a finding that could lead to new therapies.
The research solves a 16-year medical mystery by identifying the proteins in a disease-blocking substance secreted in the blood of ”long-term non-progressors” – patients infected with HIV who never get sicker and never develop full-blown Aids.
In a study appearing on Friday in Sciencexpress, the online version of the journal Science, researchers at Rockefeller University and the Aaron Diamond Aids Research Center in New York said they used a new protein-identification tool to analyze CAF, the anti-HIV substance.
They found that CAF contains natural proteins known as alpha-defensins. These disease-fighting proteins were first discovered in 1985 and were known to play a role in protecting the body from bacteria and infections.
”We are most gratified to help solve the mystery around CAF,” said Dr. David Ho, leader of the research team at Aaron Diamond. Ho said his group conducted tests that proved that three types of alpha-defensins, 1, 2 and 3, work together to inhibit HIV. He called the proteins ”natural peptide antibodies” that work in concert to prevent HIV from reproducing.
Ho said the researchers do not understand how the defensin proteins act against HIV and are still uncertain if they can be used as a drug.
”It is not entirely clear that we can turn this discovery into a useful therapeutic,” said Ho. He said the protein molecule is very large and the researchers are trying to make a smaller version that may act more powerfully against HIV.
”This will not be the ultimate solution,” said Ho, ”but it could be another weapon in the arsenal against HIV.”
Ho said that apparently a kind of white blood cells, called CD8 T cells, and another kind of immune system cells, called neutrophils, make alpha-defensins 1, 2 and 3 in most people, but for unknown reasons only some are protected against the progression of HIV.
”With HIV infection, the capacity to make alpha-defensins is lost, but it is preserved in the long-term non-progressors,” Ho said.
Susan Plaeger, an Aids scientist at the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health, said the study by Ho and his group is important ”but it may not be the end of the story.”
She said there probably are other immune system proteins yet to be identified that also inhibit HIV.
”Defensins are active against a number of other microbes, so I am sure there will be a push to develop these as therapeutic agents,” said Plaeger. – Sapa-AP