The mechanism of an AIDS vaccine candidate filmed in vivo

December 22, 2015

Using innovative technology, scientists from the Institut Pasteur and Inserm have filmed in vivo the process by which an AIDS vaccine candidate, developed by the French Vaccine Research Institute and the ANRS, triggers the immune response. This previously unseen footage clearly shows how the vaccine recruits the immune cells needed to destroy infected cells. These results, published in the journal Nature Medicine on December 21, 2015, shed new light on the mode of action and potential of this vaccine.

The aim of the study conducted by scientists from the Dynamics of Immune Responses Unit (Institut Pasteur / Inserm / VRI), directed by Inserm research director Philippe Bousso, was to observe the effect of the HIV/AIDS vaccine candidate MVA-HIV - currently undergoing clinical trials by the French Vaccine Research Institute (VRI) and the ANRS - on the immune response.

The scientists administered the vaccine to healthy mice, then observed in real time how cells from the immune system were mobilized to the lymph node, the organ where the vaccine response is developed, in just a few hours.

For the first time, using a powerful, non-invasive microscopic imaging technique, the scientists were able to watch in vivo and in real time as the vaccine induced the formation of the inflammasome, a complex assembly of proteins with a highly specific structure which appears in macrophages, the first immune cells targeted by the vaccine.

The inflammasome promotes the maturation of the chemical messenger interleukin (IL)-1 but also induces macrophage death, thereby releasing this inflammatory messenger in the lymph node. This signal triggers a 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.

These in vivo films have given the scientists a detailed picture of the main stages in the mechanistic action of this vaccine and 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," commented Philippe Bousso. "Our research demonstrates the potential of the vaccine candidate MVA-HIV to trigger a significant, diverse immune response."
This research was supported by the French Vaccine Research Institute, the French Foundation for Medical Research and the European Research Council (ERC).

Image/ film: In green, the cells targeted by the MVA-HIV vaccine soon activate the inflammasome (circled green spots) and die. This signal triggers a mass mobilization of immune cells. © Institut Pasteur

Institut Pasteur

Related Immune System Articles from Brightsurf:

How the immune system remembers viruses
For a person to acquire immunity to a disease, T cells must develop into memory cells after contact with the pathogen.

How does the immune system develop in the first days of life?
Researchers highlight the anti-inflammatory response taking place after birth and designed to shield the newborn from infection.

Memory training for the immune system
The immune system will memorize the pathogen after an infection and can therefore react promptly after reinfection with the same pathogen.

Immune system may have another job -- combatting depression
An inflammatory autoimmune response within the central nervous system similar to one linked to neurodegenerative diseases such as multiple sclerosis (MS) has also been found in the spinal fluid of healthy people, according to a new Yale-led study comparing immune system cells in the spinal fluid of MS patients and healthy subjects.

COVID-19: Immune system derails
Contrary to what has been generally assumed so far, a severe course of COVID-19 does not solely result in a strong immune reaction - rather, the immune response is caught in a continuous loop of activation and inhibition.

Immune cell steroids help tumours suppress the immune system, offering new drug targets
Tumours found to evade the immune system by telling immune cells to produce immunosuppressive steroids.

Immune system -- Knocked off balance
Instead of protecting us, the immune system can sometimes go awry, as in the case of autoimmune diseases and allergies.

Too much salt weakens the immune system
A high-salt diet is not only bad for one's blood pressure, but also for the immune system.

Parkinson's and the immune system
Mutations in the Parkin gene are a common cause of hereditary forms of Parkinson's disease.

How an immune system regulator shifts the balance of immune cells
Researchers have provided new insight on the role of cyclic AMP (cAMP) in regulating the immune response.

Read More: Immune System News and Immune System Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to