An HIV vaccine under development has shown potential to protect people around the world from the virus, new research has found, after nearly a 40-year quest for an Aids vaccine.
The treatment, which aims to provide immunity against various strains of the virus, produced an anti-HIV immune system response in tests on 393 people, a study in the Lancet found.
Using a new method called the "mosaic" vaccine, the vaccine showed potential to protect people against the many types of virus that cause Aids.
According to the findings published last week, the vaccine improved the immune responses against HIV during a clinical trial involving nearly 40 healthy adults.
The mixture of HIV strains in the "mosaic" vaccine is delivered using a non-replicating common-cold virus. The "mosaic" is one among the only five experimental HIV vaccines that have proceeded to efficacy human trials to date.
Tests on a new vaccine also stopped two-thirds of monkeys contracting a virus similar to HIV.
“I would say that we are pleased with this data so far, but we have to interpret the data cautiously. We have to acknowledge that developing an HIV vaccine is an unprecedented challenge, and we will not know for sure whether this vaccine will protect humans,” said study co-author Prof Dan Barouch, a professor at Harvard Medical School.
For the experiment, the researchers recruited 393 healthy, non-infected adults aged between 18 and 50 years from 12 clinics in Rwanda, Uganda, South Africa, Thailand, and the United States.
These participants were then divided into two groups: First, those who were injected one of seven vaccine combinations or a placebo, and second, those who were injected with four vaccinations over the course of 48 weeks.
All of the vaccine combinations produced an anti-HIV immune system response and were found to be safe.
The volunteers were also injected with the common-cold virus to boost their immune system once at the start of the trial and again 12 weeks later into the study.
“These results represent an important milestone,” said Prof Barouch. He also cautioned that the findings needed to be interpreted with caution.
Results of the study, published on July 6, showed that “mosaic” vaccine was able to trigger anti-HIV immune responses in healthy individuals. At this level, the vaccine proved to be capable of protecting the participants from the deadly virus.
Previous attempts at HIV vaccines have been limited to specific strains of the virus found in certain parts of the world.
But with the "mosaic" vaccine, scientists have developed a treatment made up of pieces of different HIV viruses. The hope is that it could offer much better protection against the almost unlimited number of HIV strains found across the world.
Though the vaccine triggered a response in the immune system of the people who took it, it is not clear if this would be enough to fight off the virus and prevent infection.
“The challenges in the development of an HIV vaccine are unprecedented, and the ability to induce HIV-specific immune responses does not necessarily indicate that a vaccine will protect humans from HIV infection,” he added.
About 37 million people worldwide live with HIV or Aids, and there are an estimated 1.8 million new cases annually. But despite advances in treatment for HIV, both a cure and a vaccine for the virus have so far remained elusive. No licensed prophylactic HIV-1 vaccine exists.
While news of the new results creates an optimistic picture, scientists are fast to temper the optimism, saying the process still has a long way to go.
Inventing a vaccine has proved an immense challenge for scientists, in part because there are so many strains of the virus, but also because HIV is clever at mutating to elude attack from the human immune system.