Researchers find natural proteins that may block progression of HIV infection

WASHINGTON -- In research that solves a 16-year medical mystery, scientists have identified a group of proteins that inhibit the progression of HIV in people who are resistant to the virus that causes AIDS.

The study, using a new protein-identification tool, identified the proteins in a disease-blocking substance, called CAF. Researchers discovered in 1986 that CAF was secreted in the blood of "long-term progressors" -- patients infected with HIV who never get sicker and never develop full-blown AIDS. But efforts to unlock the proteins in CAF have failed, until now.

Researchers at Rockefeller University and the Aaron Diamond AIDS Research Center in New York said the proteins in CAF are part of a large family of disease-fighters known as alpha-defensins. These natural antibiotics were first discovered in 1985 and were known to play a role in protecting the body from bacteria and infections. The new study finds they also inhibit HIV.

"We are most gratified to help solve the mystery around CAF," said Dr. David Ho, leader of the research team at Aaron Diamond. He is senior author of a study appearing Friday in Sciencexpress, the online version of the journal Science.

Ho said his group did tests that proved 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.

Researchers still don't know how the defensin proteins act against HIV and are still uncertain if the natural compounds can be used as a drug against the virus, he said.

"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.