Dubai, United Arab Emirates (CNN) — The ability of an experimental HIV vaccine to broadly neutralize antibodies was discovered among a small group of volunteers during a Phase 1 study.
The results indicate that a two-dose regimen of the vaccine, eight weeks apart, can elicit immune responses against HIV.
The vaccine, known as eOD-GT8 60mer, contributed to a 97% broadly neutralizing antibody count among 36 people, according to researchers at Scripps Research, the Fred Hutchinson Cancer Center, the National Institutes of Health, and other institutions in the United States and Sweden.
Antibodies are proteins made by the immune system to help fight infection.
It is known that broadly neutralizing antibodies work to neutralize many genetic variants of HIV, but it was difficult to obtain them through vaccination.
“Learning how to induce broadly neutralizing antibodies against pathogens with a large diversity of antigens, such as HIV, influenza, hepatitis C virus, or the betacurone family of viruses, presents a major challenge for vaccine design,” the researchers wrote.
The International AIDS Vaccine Initiative announced the start of this first phase clinical trial in 2018, to assess the safety of eOD-GT8 60mer and the immune responses it can induce.
The trial included 48 healthy adults, ages 18 to 50, who were enrolled at two sites: George Washington University in Washington and Fred Hutchinson Cancer Center in Seattle.
Among the participants, 18 people received the 20 microgram dose of the vaccine. Eight weeks later, the group received the same dose of the vaccine plus an adjuvant.
And 18 people received a 100 microgram dose of the vaccine. Eight weeks later, the group received the same dose of the vaccine plus an adjuvant.
Twelve participants received two placebo doses of saline, eight weeks apart.
The adjuvant is known as AS01B, which was developed by pharmaceutical company GSK. Vaccines and placebo were administered into the arm muscle.
The researchers collected and analyzed immune cells in the blood and lymph nodes of the participants during the study, while examining how the B cells responded to the vaccine.
It is reported that B cells are a type of white blood cell that makes antibodies in the immune system.
After the first immunization, all vaccine recipients produced antibodies produced by the EOD-GT8 60mer vaccine. Those vaccine-induced responses increased after the second vaccination, the researchers wrote.
Another phase 1 study on this vaccine candidate is underway, said Dr. Julie McElrath, senior vice president and director of the Division of Vaccine and Infectious Diseases at the Fred Hutchinson Cancer Center.
Last year, more than 38 million people were living with HIV or AIDS worldwide. More than 20 clinical trials of an HIV vaccine were underway worldwide, according to the International AIDS Vaccine Initiative.
And many people in the United States have turned to daily HIV prevention pills or frequent injections, known as PrEP, to reduce their risk of infection.
But the availability of an HIV vaccine would make protection from the virus easier.