WASHINGTON -- The AIDS virus has hideouts deep in the immune system that today's drugs can't reach. Now scientists finally have discovered how HIV builds one of those fortresses -- and they're exploring whether a drug already used to fight a parasite in developing countries just might hold a key to break in.
Researchers have long struggled unsuccessfully to attack what they call reservoirs of dormant HIV, and the new work is in very early stages.
But University of Rochester scientists say it may be fairly straightforward to attack one of these reservoirs, blood cells called macrophages that HIV hijacks and turns into viral hideaways.
The new discovery shows the exact s.jpg that HIV takes to do that -- and found that some existing drugs, including a long-used treatment for leishmaniasis called miltefosine, can block the main step and thus cause these cells to self-destruct.
"It's a very smart virus," said lead researcher Dr. Baek Kim. "They have to have a very good fence to protect their house for a long time. ... Get rid of the fence, and now their house is gone."
Today's drugs have turned HIV from a quick death sentence into, for many, a chronic infection. Yet those drugs don't eliminate HIV, because they can't reach the two known pools of cells where the virus can lie dormant, ever ready to resurface.
So-called memory T cells form one such pool. As the name implies, these are the cells that ensure if you get, say, measles as a child, you're forever immune. They live for years, even decades, making them a logical HIV hideout, and one that scientists have repeatedly sought to dismantle to no avail.
Macrophages, another type of immune cell, form the second pool. They roam the body looking for invaders like bacteria to gobble up. If they get harmed, such as becoming infected by a virus, they're supposed to commit suicide. But HIV instead k.jpg them alive long past their normal lifespan.
"Up to now, nobody has really thought about how to eliminate the macrophage reservoir," said Dr. Kuan-Teh Jeang, an HIV specialist at the National Institutes of Health. "The imagination now has turned toward, 'How do we eliminate reservoirs?' ... The best way to address our problem is to simply kill those cells."
The Rochester team found that HIV produces a protein that turns on a particular cell-survival pathway. After a multistep process, it ultimately activates an enzyme called Akt that in turn prevents cell suicide, the researchers reported Thursday online in the journal Retrovirology.
That was good news, Kim said, because the Akt pathway is a culprit in certain cancers -- meaning oncologists have been trying to target it for some time. So Kim put human HIV-infected macrophages in lab dishes and started adding drugs known to block the Akt pathway to see if any killed the cells.
He had luck: Miltefosine and a cousin named perifosine both rapidly killed the macrophages, thus depriving HIV of this hideout.
Perifosine is currently being studied as a possible cancer drug. But miltefosine is known to be safe through its use in leishmaniasis patients. So Kim's goal is to rapidly study the already available miltefosine in animals to see if it truly targets infected macrophages well enough to then test in HIV patients.
"The evidence they show is in fact pretty good," said NIH's Jeang, who says the next step should be a test of miltefosine in monkeys infected with SIV, the monkey version of the AIDS virus.
National Black HIV/AIDS Awareness Day events scheduled
COLUMBIA — Events will be held around the state Thursday, Feb. 7, to highlight the impact of HIV/AIDS on black communities, the state Department of Health and Environmental Control has announced.
“South Carolina continues to have a disproportionate number of HIV/AIDS cases among African-Americans,” said Shauna Hicks, DHEC’s newly appointed director of the Office of Minority Health. “We must continue, and increase, culturally competent and sensitive prevention programs in our health departments and community organizations.”
Hicks said DHEC will partner with community-based organizations to sponsor free HIV testing and HIV educational forums on the eighth annual National Black HIV/AIDS Awareness Day at housing communities, churches and community centers statewide.
Different tests will be offered, she said, including the traditional blood draw method and the rapid test, which provides preliminary results in less than an hour.
“The theme, ‘Prevention is Power,’ emphasizes the strength in the actions that African-Americans can take,” Hicks said. “Those include learning the facts about HIV, knowing their HIV status and taking steps to make a difference in their communities.
“By knowing their HIV status, people can protect their health and the health of their loved ones.”
According to DHEC statistics:
* Blacks account for 30 percent of the state’s population, yet 72 percent of the recently diagnosed HIV/AIDS cases in South Carolina.
* Blacks have been hardest hit by the epidemic. Nearly seven of every 10 men and eight of every 10 women diagnosed are black.
* Eighty percent of those 15 to 24 years old who are newly diagnosed with HIV/AIDS in South Carolina are black.
To heighten the state’s responsiveness to the disproportionate impact among blacks, DHEC’s STD/HIV Division has named Lewis Hicks consultant for its People of Color Initiatives. He will lead the division’s efforts among minority communities by identifying effective strategies to improve STD/HIV prevention services and providing technical assistance to community organizations.
For information on events and HIV testing sites in local communities, call DHEC’s South Carolina AIDS/STD toll-free hotline at 1-800-322-AIDS (2437).