Researchers from the Institut Pasteur and Inserm have filmed in vivo the process by which the HIV/AIDS vaccine candidate MVA-HIV, sparks immune response and how it recruits immune cells needed to destroy infected cells. The result of the study, conducted by scientists from the Dynamics of Immune Responses Unit, was published in the journal Nature Medicine.

Per the press release, researchers were able to see in real-time how cells from the immune system were mobilized to the lymph node few hours later after the vaccine had administered to healthy mice. For the study, a powerful, non-invasive microscopic imaging technique was used. With it, the researchers were able to see how the vaccine induced the formation of the inflammasome, a complex assembly of proteins with a highly specific structure.

The inflammasome – a multiprotein responsible for activation of inflammatory processes – appears in macrophages, the first immune cells targeted by this newly developed vaccine.

The inflammasome promotes the maturation of the chemical messenger known as interleukin (IL)-1. It also induces macrophage death, which triggers the release of this inflammatory messenger in the lymph node. As a result of the release, chain reaction – which assembles several key players of the immune system in the lymph node, including killer cells, which are vital for the vaccine response – takes place.

These in vivo films not only have provided the researchers a detailed pictures of how this HIV/AIDS vaccine candidate MVA-HIV works in its main stages, but have also highlighted an important pathway that orchestrates the effective mobilization of the immune response.

“This is the first time that the formation of this original structure, the inflammasome, has been observed in vivo and in real-time,” said Philippe Bousso, one of the authors of the study. “Our research demonstrates the potential of the vaccine candidate MVA-HIV to trigger a significant, diverse immune response.”

Sources: Institut Pasteur, In Vivo Imaging Of Inflammasome Activation Reveals A Subcapsular Macrophage Burst Response That Mobilizes Innate And Adaptive Immunity