Many steps forward have been made in the fight against AIDS: drugs are increasingly effective and simple to use, and pre-exposure prophylaxis therapies guarantee high protection for risk categories. To stop this epidemic once and for all, which has continued to claim victims for 40 years now, a vaccine would be needed, and this is something that continues to elude the efforts of scientists. For this reason, every small step forward is viewed with extreme interest by the scientific community. And in recent days a particularly big one has arrived: a vaccine that would finally seem to push the production of neutralizing antibodies, the weapons with which our body can defend itself from the aggression of HIV.
It is obviously early to claim victory. Also because the vaccine developed in the laboratories of the Duke Human Vaccine Institute, as reported by a study published in the journal Cell, has so far proved problematic in terms of safety in human trials, and has forced its developers to interrupt the clinical trial in which was being tested, and to reformulate the vaccine. Having said that, as we were saying, the new results are an important step in what – write the authors of the study – could finally be the path that will lead to the development of an effective vaccine against HIV.
The vaccine in question, in fact, is the first to have demonstrated that it can stimulate the creation of the so-called “HIV-1 neutralizing antibodies”, i.e. antibodies that are able to neutralize all viruses belonging to HIV subtype 1 (the most common) . An achievement that is not to be taken for granted, given that the virus is known for its ability to mutate quickly and evade the recognition mechanisms of our immune system. It is linked to the ability of these neutralizing antibodies to target some structures of the virus that tend to be preserved even when it mutates, and which are essential for its replication.
In patients infected with HIV, similar antibodies emerge rarely, approximately in 10-25% of cases. Speaking of vaccines, however, until now it has never been possible to obtain them. The trial of the new vaccine, launched in 2019, involved 24 healthy participants, 20 of whom received the vaccine (the other four were given a placebo).
How the AIDS vaccine works
Before having to suspend the trial due to a serious adverse reaction to one of the drug's components, researchers observed the production of low levels of neutralizing antibodies after just two administrations of the vaccine. The vaccine, as we were saying, was modified to replace the component that created safety problems, and the trial resumed. There is no point in expecting miracles any time soon, however, but the vaccine developers are confident: if their technique worked once, it is likely to do so again, and so it could now be a matter of time before a vaccine is formulated truly effective against HIV. The key to preventing the virus from continuing to claim victims once and for all.
“Our work is a fundamental step forward because it shows that it is possible to induce the production of neutralizing antibodies against the most complex type of HIV, using vaccination,” explains Barton Haynes, director of the Duke Human Vaccine Institute. “The next step will be to induce the production of more powerful neutralizing antibodies, targeted to other sites in order to prevent the virus's ability to escape the immune system. We are not yet at the goal, therefore, but the path to follow is now much clearer”.