Jefferson scientists find rabies-based vaccine could be effective against HIV

April 03, 2007

(PHILADELPHIA) -- Rabies, a relentless, ancient scourge, may hold a key to defeating another implacable foe: HIV. Scientists at Jefferson Medical College in Philadelphia have used a drastically weakened rabies virus to ferry HIV-related proteins into animals, in essence, vaccinating them against an AIDS-like disease. The early evidence shows that the vaccine - which doesn't protect against infection - prevents development of disease.

Reporting April 1, 2007 in the Journal of Infectious Diseases, the scientists showed that two years after the initial vaccination, four vaccinated non-human primates were protected from disease, even after being "challenged" with a dangerous animal-human virus. Two control animals developed an AIDS-like disease.

Matthias Schnell, Ph.D., professor of microbiology and immunology at Jefferson Medical College of Thomas Jefferson University, and his co-workers tested the effects of inserting two different viral proteins into the rabies virus genome, and using such viruses-based vaccines in preventing disease in rhesus macaques. One was a glycoprotein on the surface of HIV, while the other was an internal protein from simian immunodeficiency virus (SIV). They used the latter because HIV does not cause disease in monkeys.

The idea was that such rabies' vehicles, or "vectors," would help attract a strong response from the animal's immune system, though the rabies virus used cannot cause disease. Such vectors are based on a type of rabies vaccine strain that has been used for more than 20 years in oral vaccines against rabies in wildlife in Europe. The study was aimed at studying the safety and effectiveness of the rabies vaccine approach against HIV and related diseases.

Four macaques were immunized with both vaccines, while two animals received only a weakened rabies virus. After they gave the animals an initial vaccination, they then tried two different immune system boosts, but didn't see enhanced immune responses. They then developed a new vector, a viral surface protein from another virus, vesicular stomatitis virus (VSV). Two years after the initial immunization, they gave a booster vaccine with the rabies-VSV vector, and saw SIV/HIV-specific immune responses.

The group then challenged the animals with SIV and measured various parameters of infection, such as immune system CD4 cell count, amount of virus in the bloodstream and immune system antibody response. They found that those animals that were given the test vaccine could control the infection. The control animals without the experimental vaccine had high levels of virus and a loss of CD4 cells.

"We still need a vaccine that protects from HIV infection, but protecting against developing disease can be a very important step," Dr. Schnell says, noting that he and his colleagues aren't sure how long the viral immunity will last.

According to Dr. Schnell, the study demonstrated a "proof of principle" - that is, that the method used is technically possible. He says that the results indicate the need for future studies in larger groups of animals, and that these currently are underway. In addition, one key question remains unanswered: Is such a rabies-based vaccine feasible as an HIV vaccine in humans?
-end-
Contact: Jackie Kozloski 215-955-6300 After Hours: 215/955-6060

Thomas Jefferson University

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
Brightsurf.com 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 Amazon.com.