Small advancements make big waves in the decades-long search for an HIV vaccine, and University of Miami researchers are optimistic that their latest findings are significant: They have developed a vaccine that triggers an immune system response strong enough to kill a model AIDS virus in mice.
The vaccine is still in the early stages of development, said Geoffrey W. Stone, a UM assistant professor of microbiology and immunology who led the research study published in February’s Journal of Virology.
“But in those modest beginnings,” he said, “we have had some very dramatic results.”
The vaccine developed by Stone and his team can prevent mice from becoming infected with HIV, he said, by targeting a specific receptor in the immune system to trigger a significant T-cell response to the virus.
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The receptor is called CD40, and the vaccine uses a special form of the receptor’s natural binding protein to enable the immune system’s dendritic cells to signal the presence of HIV.
“We’re trying to get a magic bullet,” Stone said, “that can bring information about HIV to dendritic cells.”
Unlike standard vaccines, which use untargeted antigen to generate an immune system response, the approach developed by Stone and his team attaches an HIV antigen to the binding protein, which then generates the better immune response by targeting the antigen to dendritic cells.
The immune system response among vaccinated mice was strong enough to fend off infection by more than 10 million model viruses containing an HIV antigen, according to the study.
The findings also offer hope for development of vaccines for other diseases because large numbers of T-cells can protect against influenza, malaria and cancer.
The next step is trials on larger animals, and eventually clinical trials on people — a process that could take 10 years or longer.
Stone acknowledged that there are many research projects managing clinical trials for an HIV vaccine, and that his team’s approach is “just one” of those efforts.
“We’re all very committed to getting an HIV vaccine,” he said. “Part of what we hope is that it can be combined with other concepts and work that has been done by other groups.”
Work to find an HIV vaccine has particular urgency in Miami-Dade, where nearly 35,000 adults and children were living with the disease in 2013, according to the Florida Department of Health.
Miami-Dade has consistently been among the nation’s top five metropolitan areas for HIV infection, said Sandra Gracia Jones, an assistant professor at Florida International University’s Wertheim College of Nursing and Health Sciences.
Jones said antiretroviral drug treatments have allowed people to live longer with HIV than in the past, but that despite advances in medical therapies — and the ongoing research into vaccines — the best approach is prevention, and the most effective methods for prevention have not changed.
“There’s nothing new in how HIV is transmitted. For the most part it’s sexual transmission,’’ she said. “Prevention has been the same: use a condom, or some type of barrier.
“Why 22 years later we’re still getting new cases of HIV infection each year, in Miami-Dade and throughout country, is a good question.”