A vaccine developed to treat HIV allowed half of the volunteers who tried it to be freed, at least temporarily, from the need to take antiretroviral drugs on a daily basis.
The research, published in the journal Science Translational Medicine, "pave the way for further studies with the ultimate goal of a functional treatment: the suppression of HIV multiplication for long periods, or even for a lifetime, without antiretroviral therapy," the Spanish researchers estimate.
However, tests have shown that the vaccine loses its effectiveness within a maximum of one year.
The therapeutic vaccine, which aims to treat the infection rather than prevent it, contains dendritic cells isolated from the patients' own blood. In the laboratory, these cells are exposed to HIV viruses that have been previously heat-inactivated, so they are "trained" to recognize the threat.
"What we did was to instruct the immune system so that it learns to destroy the virus, which normally doesn't happen," explains Felipe Garcia, first author of the publication from the University of Barcelona. The AIDS virus is also notorious for its ability to attack the very immune system that normally protects against viruses.
Twelve weeks after the vaccine, HIV levels had fallen by more than 90% in 12 of the 22 patients who were vaccinated. However, a similar reduction was recorded in one of the 11 patients in the control group who received a placebo vaccine.
The vaccine's effectiveness had declined after 24 weeks, however, with only seven patients maintaining a 90% reduction. An increase in virus levels was also recorded in the control patient who had initially shown improvement.
One year after the first vaccination, all patients were forced to return to standard treatment with antiretroviral drugs.
"Although we do not yet have a working treatment," the researchers commented, "the results we publish today leave open the possibility of an effective therapeutic vaccine, or a combination of strategies that includes a vaccine.".
