July 21, 2005-- Posted at 2:50 PM CDT
(HealthDay News) -- When it comes to preventing transmission of HIV, public health officials have long advocated abstinence and, barring that, condoms -- both of which have been a tough sell.
Now, scientists think they may be on the road to a third alternative: a bacteria-based barrier to keep HIV at bay.
Federal researchers report in this week's issue of the Proceedings of the National Academy of Sciences that they have managed to piggyback a germ-killing agent onto harmless bacteria living naturally in the body's mucous membranes. Ultimately, the approach could protect the body against HIV by killing the virus before it can start to feel at home.
While the work is in the preliminary stages, it suggests that people might be able to just take a pill and get a month's worth of protection, said study co-author Dean Hamer, senior staff scientist at the National Cancer Institute. "It's promising, but still early," he said.
According to some estimates, 14,000 people become infected with the AIDS virus worldwide each day. In 80 percent of cases, transmission occurs when the virus makes its way through vaginal or anal membranes during sex.
These membranes, similar to those that filter germs in the nose, are home to a "biofilm" that includes "lots of different types of bacteria, mucous and other secreted products," Hamer said. "They're well-known to have a protective effect against pathogenic bacteria."
These good germs manage to fend off bad germs by giving off toxic substances and by simply being in the way, Hamer explained.
As part of a research project, Hamer and colleagues tried to colonize the mucous membranes of rats with a peptide -- a kind of protein -- that fights off the AIDS virus.
The researchers successfully managed to genetically engineer the bacteria to transport the anti-HIV peptides into the rectums, colons, small intestines and vaginas of the rats. The peptides, similar to those used in the HIV-suppressing drug Fuzeon, remained there for weeks or months, Hamer said.
Tests in primates will determine if the approach can actually stop HIV. The strategy seems to be "fairly benign" in terms of side effects, Hamer said, but only further research will determine its safety.
If the strategy does work, doctors might be able to deliver good germs to the mucous membranes via pill or suppository, Hamer said.
The idea of a pill is promising because taking a drug is more foolproof than using a condom, said Johns Hopkins University research scientist Kevin Whaley, who is also chief executive officer of MAPP Biopharmaceutical, a company that works to develop anti-bacterial drugs.
Delivering agents with the help bacteria could even help doctors inoculate people with vaccines, said Whaley, who's familiar with the findings. "All of us want to have technology which doesn't have to be delivered with a shot," he said.
Ultimately, the approach could add another weapon to the anti-HIV arsenal, he said. "The issue is that we need multiple options."
By Randy Dotinga, HealthDay Reporter
Learn more about HIV prevention from the Center for AIDS Prevention Studies (www.caps.ucsf.edu ).
SOURCES: Dean Hamer, Ph.D., senior staff scientist, National Cancer Institute, Bethesda, Md.; Kevin J. Whaley, Ph.D., research scientist, Johns Hopkins University, and chief executive officer, MAPP Biopharmaceutical, San Diego; June 18-22, 2005, Proceedings of the National Academy of Sciences