An experimental HIV vaccine appears to have passed its first human test. In a recently published study, the vaccine candidate produced the kind of immune response scientists had hoped for in 97% of recipients. Importantly, the vaccine also appeared to be safe and well tolerated.
The candidate vaccine is known as eOD-GT8 60mer and was developed by researchers at the Scripps Research Institute. The phase I trial testing eOD-GT8 60mer, first announcement in 2018, was sponsored by the International AIDS Vaccine Initiative (IAVI). This is part of a large collaboration between scientists at Scripps, the National Institutetes of Health, the Fred Hutchinson Cancer Center and other groups in the United States and Sweden. It involved 48 healthy participants, 36 of whom received two doses of the vaccine eight weeks apart (these participants were divided into a low- and high-dose group).
HIV infection can now be effectively managed with lifelong antiviral therapy. But the virus has the ability to cleverly change its structure once inside the body, making it difficult for the immune system to recognize it for long. This means that long-lasting immunity to the virus, at least in most cases, has remained elusive. But we’ve known for decades that some people can produce largely neutralizing antibodies to the virus that can track it. And ever since, scientists have been in pursuit of the elusive HIV vaccine capable of creating these antibodies.
A new method to obtain these antibodies, known as germline targeting strategy, is represented by eOD-GT8 60mer. Simply put, the first dose of vaccine attempts to prime a rare, select group of B cells into a state where they could produce these antibodies. Subsequent boosts are then believed to reactivate these cells, ultimately leading to long-lasting and largely neutralizing antibodies against HIV. And in the conclusions of this new trial, published Friday in Science, the first part of this strategy seems to work.
The researchers found that 35 out of 36 volunteers appeared to generate the precursors to these broadly neutralizing antibodies and that this immune response only increased in strength after the second dose.
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“The hope is that if you can induce this kind of immunity in people, you can protect them from some of these viruses that we’ve had a very difficult time designing effective vaccines for,” said Timothy Schacker, director of the HIV program. medicine at the University of Minnesota Medical School, which was not involved in the research, Told CNN. “So this is an important step forward.”
Phase I trials are primarily designed to test the safety of an experimental treatment. And the vaccine also had a favorable safety profile, the researchers wrote, with no serious vaccine-related adverse events reported. The results are also timely, given that yesterday was World AIDS Day.
This study is only a proof of concept, however, the authors note. More research in humans will be needed to confirm the early findings seen here and to show that broadly neutralizing antibodies can be reliably coaxed by boosters. Any truly effective vaccine should also create a broad T-cell response to HIV, because T-cells are often a crucial aspect of our immunity to germs. But if this research continues to bear fruit, scientists may one day be able to create vaccines that not only provide long-lasting protection against HIV, but also against other evasive diseases like hepatitis C, influenza and covid-19.
Another phase I trial of eOD-GT8 60mer is already underway, and other similar vaccine candidates are in the pipeline tested also in early human trials.
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