The treated mice in the study appeared to have 100 percent protection against HIV. That doesn't mean the strategy will work in people. But several experts were impressed.
"This is a very important paper (about) a very creative idea," says the government's AIDS chief, Dr. Anthony Fauci. He didn't take part in the research.
The new study involved injecting mice with a protective gene, an idea that's been tested against HIV infection in animals for a decade.
In the nearly 30 years since HIV was identified, scientists haven't been able to find a vaccine that is broadly effective. One boost came in 2009, when a large study in Thailand showed that an experimental vaccine protected about a third of recipients against infection. That's not good enough for general use, but researchers are now trying to improve it.
Researchers reported the new results in mice online Wednesday in the journal Nature. They hope to test the approach in people in a couple of years. Another research team reported similar success in monkeys in 2009 and hopes to start human tests even sooner.
A traditional vaccine works by masquerading as a germ, training the body's immune system to build specific defenses in case the real germ shows up. Those defenses are generally antibodies, which are proteins in the blood that have just the right shape to grab onto parts of an invading virus. Once that happens, the virus can't establish a lasting infection and is cleared from the body.
Scientists have identified antibodies that neutralize a wide range of HIV strains, but they've had trouble getting people's immune systems to create those antibodies with a vaccine.
The gene-injection goal is straightforward. Rather than trying to train a person's immune system to devise effective antibodies, why not just give a person genes for those proteins? The genes can slip into cells in muscle or some other tissue and make them pump out lots of the antibodies.
The mouse work is reported by David Baltimore and colleagues at the California Institute of Technology.
Ordinary mice don't get infected with HIV, which attacks the immune system. So the research used mice that carried human immune system cells.
Baltimore's team used a harmless virus to carry an antibody gene and injected it once into a leg muscle. The researchers found that the mice made high levels of the antibody for more than a year. The results suggest 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 certain blood cells that results from HIV infection. Baltimore said researchers couldn't completely rule out the possibility of infection, but that their tests found no evidence of it. He said a few hundred mice appeared to be protected.
The work was funded by the federal government and the Bill and Melinda Gates Foundation. Baltimore said his lab has filed for patents.
"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 said he has discussed doing a human trial with federal regulators and is preparing an application for permission to go ahead. If all goes well, a preliminary experiment to test the safety of the approach might begin in about a year, he said. Baltimore said his group is also planning human experiments that he hopes will start in the next couple years.
Fauci, who is director of the National Institute of Allergy and Infectious Diseases, cautioned that mouse results don't always pan out in human studies. He also said both the gene approach and standard vaccines should be pursued because it's not clear which will work better.
The biggest headache for Jimu Zishi is the rainy or snowy weather, as it would make the rugged mountain paths a tougher challenge and her shoes would always become worn-out after such a trip, says the 34-year-old woman.
Her mother hopes that she quit the job, but Jimu Zishi has persisted.
"The pains are worthwhile as I feel I have to play my role when HIV is taking its toll on my locals," she says.
Locked in deep mountains, China's largest Yi community in Liangshan, a prefecture which administers Zhaojue, can not yet escape the ravage from the demon of AIDS.
A juncture of Sichuan and Yunnan, a province adjacent to the drug source of the Golden Triangle in Southeast Asia, ethnic Yi people in Liangshan unfortunately falls into a victim of heroin, and the Yi communities have to face greater risks of HIV infections because of popular needle sharing among drug users.
A total of 24,768 HIV carriers have been reported in the prefecture as of September, 2011 while the number was 21,565 last year. It is recorded that there are currently 11,549 drug addicts across the prefecture.
Jimu Zishi is only one of the Yi people who have been awakened to the cruel truth -- the Yi ethnic group, one of the oldest minorities in China with a history of more than 2,000 years, will have to face a survival crisis if drugs and the virus of AIDS are not stemmed in their mountains.
HIGH PREVALENCE
Yi is not the unique case. In other major ethnic minority communities, AIDS has been spreading in a notable way.
In Xinjiang Uygur Autonomous region, the disease has been seen as a taboo for the majority of Muslim. People considered HIV carriers dirty.
So far more than 30,000 HIV carriers and AIDS patients have been reported in this region, ranking fifth in the country.
In Yunnan province and Guangxi Zhuang Autonomous Region, homes to dozens of ethnic minorities, AIDS is regarded among the high risk diseases, as these regions have witnessed rampant drug abuse and frequent cross-border marriages.
Huang, a Guangxi resident, married Nguyen, a former Vietnamese sex worker in 2004. Two years later, she suffered recurring herpes outbreaks on her face. The couple spent a lot of money but the outbreaks didn't stop. Finally a doctor suggested they take a HIV test. Both of them showed positive results.
"In Xinjiang's Yili Kazakhstan Prefecture and Yunnan's Ruili City and Longchuan County, AIDS infection rates are over one percent, which is higher than the country's average and can be categorized into high prevalence areas," said Chen Zhu, minister of health.
There are 780,000 HIV carriers and AIDS patients in China, according to Chen.
Officials and experts worry that AIDS spread in ethnic minority regions, which are economically lagging behind and poorer than most parts of China, will slow down their development and cause social instability.
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