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Biologists have found an effective defense against HIV infection?
Last reviewed: 01.07.2025
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Over the past year, scientists around the world have been studying a group of powerful antibodies that have the ability to neutralize HIV in the lab. They hoped they could create a vaccine that produces antibodies with similar properties.
Biologists at the California Institute of Technology (Caltech), led by Nobel laureate David Baltimore and Robert Andrews Millikan, a professor of biology, have come one step closer to that goal: They have developed a way to deliver these antibodies to mice, thereby effectively protecting them from HIV infection.
This new approach to HIV prevention is called Vectored ImmunoProphylaxis or VIP.
Traditional efforts to develop an HIV vaccine have focused on developing substances that trigger an effective immune response - either in the form of antibodies to block infection or T cells that attack infected cells.
"VIP has the effect of a vaccine, but it never stresses the immune system. Typically, you put an antigen or killed bacteria into the body and the immune system starts producing antibodies against it. We took only part of that equation," says lead author Alejandro Balazs.
Because mice are not susceptible to HIV, the scientists used specialized mice that had human immune cells that could respond to HIV. They used adeno-associated virus (AAV), a small, harmless virus, as a carrier to deliver genes that determine antibody production. After a single injection of AAV, the mice produced high levels of these antibodies for the rest of their lives. These antibodies also protected the mice from infection when the scientists infected them with HIV.
The team points out that the difference between mice and humans is very big - just because this approach works in mice doesn't necessarily mean it will work in people.
"We're not promising that we've actually solved the human problem," Baltimore says. "But the evidence for preventing HIV infection in mice is clear. We have work to do."
In the mouse model, VIP worked even under conditions of increased risk of HIV infection. To test the effectiveness of the antibodies, the researchers started with a one-nanogram dose of the virus, which was enough to infect most mice. When they saw that the mice given VIP did not become infected, they kept increasing the dose to 125 nanograms of the virus.
"We expected that the antibodies would not be able to protect the mice with this viral load, but this did not happen, even when we injected the mice with 100 times more virus than was needed for infection," Balazs says.
The scientists are now in the process of developing a plan to test their method in human clinical trials.
"In typical vaccine studies, the shot induces an immune response - you just don't know if it's 100% going to fight the virus," Balazs explains. "In this case, we already know that the antibodies work. My view is that if we can induce enough antibody production in people, the likelihood that VIP will be successful is actually quite high."
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