Members of the research group at Karolinska Institutet who played a leading role in the study: Fabian-Alexander Schleich, Gunilla Karlsson Hedestam, Ioannis Zygouras, Monika Ádori och Martin Corcoran.
Photo Credit: Courtesy of Karolinska Institutet
Scientific Frontline: Extended "At a Glance" Summary: Broadly Neutralizing HIV Vaccine Strategy
The Core Concept: Researchers have developed a novel vaccine strategy that successfully generates antibodies capable of neutralizing highly divergent HIV variants by presenting specially designed HIV proteins on liposomes to the immune system.
Key Distinction/Mechanism: HIV mutates rapidly, which historically allows it to evade vaccine-induced immunity. This new strategy circumvents that challenge by directing the immune system to target the viral "apex"—a highly conserved, three-dimensional structure at the top of the virus's surface protein. By immunizing macaques with liposomes linked to a selected HIV protein and administering sequential booster doses with gradually altered proteins, the immune system is trained to bypass dense sugar molecule shields and recognize features shared across many HIV variants.
Major Frameworks/Components:
- Targeting the Viral Apex: Focusing the immune response on a specific, structurally consistent region of the HIV surface protein shared across multiple viral variants.
- Liposomal Presentation: Utilizing tiny fat particles (liposomes) to simultaneously present multiple copies of the virus's surface protein, thereby amplifying the immune response.
- Sequential Booster Alteration: Gradually modifying the HIV protein in successive booster doses to artificially train the immune system to identify and attack universal viral features rather than variant-specific mutations.
Branch of Science: Immunology, Virology, and Vaccinology.
Future Application: The successful induction of broadly neutralizing antibodies in animal models provides a direct translational pathway for human medicine. Discussions are currently underway to advance this sequential immunization strategy into human clinical trials for a viable HIV vaccine.
Why It Matters: Eliciting broadly neutralizing antibodies has been one of the most significant biological hurdles in HIV research. Proving that vaccination can successfully steer the immune system toward a protected, universal part of the virus marks a critical step toward ending the global HIV epidemic.
Researchers at Karolinska Institutet, in collaboration with colleagues at The Scripps Research Institute and Emory University, have developed a new vaccine strategy that has generated antibodies capable of neutralizing highly divergent HIV variants. The study, published in the journal Nature, provides new insights into how the immune system can be guided towards a particularly protected part of the virus.
HIV mutates rapidly, making it difficult to develop an effective vaccine. One major challenge has been to stimulate the immune system to produce so‑called broadly neutralizing antibodies that recognize parts of the virus shared by many HIV variants.
In the study, the researchers focused on a small structure located at the very top of the virus’s surface protein, known as the apex, which is important for the protein’s three-dimensional structure. The apex is similar across many HIV variants but is shielded by dense layers of sugar molecules, making such binding difficult to achieve.
"We developed a strategy in which specially designed HIV proteins were attached to tiny fat particles, known as liposomes. This enabled multiple copies of the virus’s surface protein to be presented to the immune system simultaneously, thereby strengthening the immune response", says Mónika Ádori, researcher at Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet.
The vaccine strategy was tested in an animal model in which macaques were immunized with liposomes linked to a selected HIV protein and then given booster doses in which the protein was gradually altered. The aim was to train the immune system to recognize features that are shared across different HIV variants.
Resembles antibodies that develop in humans
With this strategy, all vaccinated animals developed antibodies that neutralized a wide range of HIV variants. When the researchers analyzed the antibodies in more detail, they found that they bind to the virus apex in a way like antibodies that sometimes develop in humans after long‑term HIV infection.
“The study shows that it is possible, through vaccination, to steer the immune system towards this specific part of the HIV surface protein,” says Gunilla Karlsson Hedestam, professor at the Department of Microbiology, Tumor and Cell Biology at Karolinska Institutet and a shared senior author of the study.
“This is an important step towards understanding how an HIV vaccine could be designed. Discussions are now underway about how the strategy could be taken into clinical studies,” she continues.
Funding: The study was funded by the US National Institutes of Health (NIH). The researchers report no conflicts of interest.
Published in journal: Nature
Title: Vaccination generates broadly cross-neutralizing antibodies to the HIV Env apex
Authors: Javier Guenaga, Monika Ádori, Shridhar Bale, Swastik Phulera, Ioannis Zygouras, Fabian-Alexander Schleich, Xaquin Castro Dopico, Sashank Agrawal, Miyo Ota, Richard Wilson, Jocelyn Cluff, Tamar Dzvelaia, Marco Mandolesi, Wen-Hsin Lee, Agnes A. Walsh, Mariane B. Melo, Laurent Verkoczy, Darrell J. Irvine, Martin Corcoran, Ian A. Wilson, Diane Carnathan, Guido Silvestri, Andrew B. Ward, Gabriel Ozorowski, Gunilla B. Karlsson Hedestam, and Richard T. Wyatt
Source/Credit: Karolinska Institutet | Jenny Hawkes
Reference Number: imgy042926_02
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