Researchers: New approach may outflank AIDS virus

The scientists came to the conclusion after an experiment performed on monkeys by infecting them with a closely related HIV virus, –SIV (simian immunodeficiency virus).

Before this new approach, focus was on HIV vaccines which aimed at stimulating immune system of the body to produce antibodies (killer cells), either before or after infection with HIV virus in the body. The clinical trials were disappointing and showed fall in the functioning of the immune system.

The two-phased experiment
The experiment conducted by the team headed by Dr Philip R Johnson of the hospital was performed in two phases:

In phase one of the experiment, the researchers created immunoadhesins (antibody like protein) designed to bind with SIV to develop SIV-specific immunoadhesin. SIV test model was considered since SIV is similar to HIV.

Then, the DNA of this molecule was engineered into Adeno-associated virus (AAV), which was to be used as the carrier virus (an easy method of introduction of an antibody carrying specific DNA molecules to the body).

In the second phase, the AAV viruses were delivered into muscles of the monkeys, resulting in four monkeys being immunised. After one month of this procedure, the monkeys were injected with live AIDS, causing SIV. Un-immunised monkeys were also injected with the same.

Results of the gene therapy
The scientists found the following results from this novel experiment:

• All immunized monkeys were saved from AIDS.
• Two-third of unimmunised monkeys died due to AIDS complications.
• It was observed that a high concentration of the SIV-specific immunoadhesins remained in the blood for over one year.

Ray of hope for AIDS patients
Dr. Beatrice Hahn, AIDS researcher, University of Alabama, Birmingham, who was not part of Johnson`s team, said, "It basically shows there is light at the end of the tunnel.”

According to Dr Johnson, further experimentation needs to be done to develop better molecules, including human monoclonal antibodies, if this technique is to become a trusted preventive measure to fight against HIV.

National Institute of Allergic and Infectious Diseases of the National Institutes of Health had given grants to support this study.