A therapeutic vaccine strategy tested by researchers in Barcelona has been found to be effective in controlling the level of HIV among several patients, a new study revealed.

Although results are yet to be tested in a large-scale clinical trial, scientists say the therapeutic vaccine may be a "functional cure" that allows patients to control the virus without having to take antiretroviral drugs.

Functional Cure For HIV Patients

The search for an AIDS vaccine has generated massive investments and intensive efforts, but so far, not one vaccine has come to market.

In the past, experts like Tomáš Hanke of the University of Oxford have tried out therapeutic vaccines that attempt to keep the virus at bay for months or years without drugs.

Now, in a new study, Beatriz Mothe and her colleagues from the Spanish AIDS institute IrsiCaixa tried the same strategy and used Hanke's HIV vaccine on 13 patients.

All participants had taken antiretroviral drugs on average for at least three years and began their treatments six months after being infected. This helped keep the levels of HIV in their blood undetectable in standard tests.

Researchers speculated that this had limited the virus's integration into the patients' chromosomes, leaving them with traces of infected cells. This should make it easier to contain the virus if the drugs are stopped, especially with the help of a vaccine, they said.

In the trial, participants received three shots of the therapeutic vaccine and stopped taking the antiretroviral drugs.

In a span of four weeks, eight of the patients saw the virus rebound. On the other hand, the other five patients have gone six to 28 weeks without having to restart the treatment.

For these five patients, the virus became temporarily undetectable, but it has never gone above 2,000 copies per milliliter, which is the criterion to restart treatment.

"It looks like a battle between the virus and their immune systems," Mothe told MedPage Today.

Hope For AIDS Vaccine?

Steven Deeks, a clinician from the University of California, San Francisco, said he is cautiously optimistic that the study will inspire other researchers to try the same strategy.

He said out of 50 trials on the therapeutic vaccine so far, the Barcelona study is the first one to bolster the immune system in a "meaningful way."

Mothe said that past treatment interruption trials - especially those among patients who started taking antiretroviral drugs after six months of being infected - have found only 10 percent control for their infections for more than four weeks. In the Barcelona study, the rate is 38 percent.

Deeks agreed that the study passed a milestone.

"Should the current trends persist, it is hard to argue that the vaccine strategy did not do something, but controlled studies are needed," added Deeks.

The findings of the small-scale study were presented at the Conference on Retroviruses and Opportunistic Infections in Seattle.

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