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Have biologists found effective protection against HIV infection?
Last reviewed: 23.04.2024
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For the past year, scientists around the world have studied a group of powerful antibodies that have the ability to neutralize HIV in the laboratory. They hoped they could create a vaccine that produced antibodies with similar properties.
Biologists from the California Institute of Technology (Caltech), led by Nobel Prize winner David Baltimore and Robert Andrews Milliken, a professor of biology, took a step closer to this goal: they developed a method for delivering these antibodies to mice, and thus effectively protected them from HIV infection.
This new approach to HIV prevention is called Vectored ImmunoProphylaxis (directed immunoprophylaxis) or VIP.
Traditional efforts to develop an HIV vaccine have focused on developing substances that elicit 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 does not cause a strain of the immune system.As a rule, you put the antigen or killed bacteria in the body and the immune system starts producing antibodies against it.We took only a part of this equation," says study lead author Alejandro Baláš .
Because mice are not sensitive to HIV, scientists have used specialized mice that have cells of the human immune system that are able to respond to HIV. They used adeno-associated virus (AAV) - a small, harmless virus that was used as a carrier for the delivery of genes that determine the production of antibodies. After a single injection of AAV, the mice produced high concentrations of these antibodies for the rest of their lives. These antibodies also protected mice from infection when scientists infected their HIV.
The team points out that the difference between mice and humans is very large - the fact that this approach works on mice does not necessarily mean that it will be effective in humans.
"We do not promise that we actually solved the human problem," says Baltimore. "But the evidence of preventing HIV infection in mice is obvious." We have something to work on. "
In the mouse model VIP worked even in conditions of increased risk of HIV infection. To test the effectiveness of antibodies, the researchers began by introducing a dose of the virus into one nanogram, which was enough to infect most mice. When they saw that the mice receiving the VIP did not become infected, they continued to increase doses to 125 nanograms of the virus.
"We expected antibodies to not protect mice with such a viral load, but this did not happen, even when we injected 100 times more virus into the mice than was necessary for infection," Balash said.
Now scientists are in the process of developing a plan for testing their method in clinical trials on humans.
"In typical vaccine studies, vaccination triggers an immune response - you just do not know if it will fight 100% of the virus," Balash explains. "In this case, we already know that the antibodies are working.It is my opinion that if we can cause sufficient production of antibodies in humans, then the probability that the VIP will be successful, in fact, is quite high."
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