HIV Treatment } 100% Protection in Mice
(Credit: CBS/iStockphoto)
(CBS/AP) An HIV vaccine might be years away, but scientists are hopeful that promising results from a new mice study might lead to a different approach for tackling the disease.
"This is a very important paper (about) a very creative idea," says the government's AIDS chief, Dr. Anthony Fauci, who didn't participate in the research.
Just what exactly is this novel treatment approach? For the study - published in the Nov. 30 issue of Nature - David Baltimore and colleagues at the California Institute of Technology injected mice with a gene that's thought to protect against HIV. By study's end, the mice appeared to have 100 percent protection against the infection.
Traditional vaccines protect against disease by masquerading as a germ, training the immune system to build defenses - generally antibodies - in case the real germ invades. Antibodies are proteins in the blood that have the right shape to grab onto parts of an invading virus, preventing the virus from establishing a lasting infection, clearing it from the body. Scientists have identified antibodies that neutralize several HIV strains, but they've had trouble getting people's immune systems to create those antibodies with a vaccine.
For this treatment, rather than trying to train a person's immune system to develop effective antibodies, it gives a person genes that create these proteins. The genes would slip into cells in muscle or some other tissue, causing them to churn out antibodies.
Baltimore's team used a harmless virus to carry an antibody gene and injected it once into the mouse's leg muscle. The researchers found that the mice made high levels of the antibody for more than a year. That suggests lifetime protection for a mouse, Baltimore said, although "we simply don't know what will happen in people."
Even when the mice were injected with very high doses of HIV, they didn't show the loss of blood cells that results from HIV. Researchers couldn't completely rule out the possibility of infection, Baltimore said, but their tests on a few hundred mice showed no evidence of HIV.
The study was funded by the federal government and the Bill and Melinda Gates Foundation.
"I think it's great," said Dr. Philip R. Johnson of the Children's Hospital of Philadelphia, who reported similar results in monkeys in 2009. "It provides additional evidence this is a concept that's worth moving forward."
Johnson's team wants to conduct human trials even sooner, and is preparing an application for federal regulators to go ahead with that research. If all goes well, a preliminary experiment to test the safety of the approach might begin in about a year, he said. Baltimore's group hopes to start human experiments in the next couple years.
Fauci cautioned that mouse results don't always pan out for humans. He also said both the gene approach and standard vaccines should be pursued because it's not clear which will work better.
"We're still in the discovery stage of both of them," he said.
Dr. Harris Goldstein, director of the Einstein-Montefiore Center for AIDS Research in New York, called Baltimore's findings a significant advance if it works in humans. It might lead not only to preventing infection, he said, but also a treatment for infected people.
The CDC has more on HIV vaccine research.
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