Experiments have shown that the immune system could be stimulated to wade off AIDS by improving the effectiveness of DNA vaccines. This has already been shown by researchers at the University of Pennsylvania School of Medicine who have used interleukin-15, an immune system gene, to improve the protective effect of a vaccine obtained from the DNA of simian HIV.
The researchers said that the administration of the modified vaccine provided macaque monkeys in their study with greater protection against simian HIV (SHIV) than an unmodified vaccine.
"DNA vaccine technology has great promise for the development of vaccines and immune therapeutics for a variety of infectious diseases and cancers," says senior author Dr. David B. Weiner, Professor of Pathology and Laboratory Medicine.
While previous studies had suggested that the technology could induce immune responses safely, 'improving the immune potency of this platform is critical for further development in humans,' said the researchers.
Published in the online edition of the Proceedings of the National Academy of Sciences, the research builds on previous work aimed at engineering a more potent immune response to SHIV DNA vaccine technology.
In previous research, mouse models studied showed that the cytokine IL-15, a substance that can improve the body's natural response to infection and disease, helps better immune responses and protection. The present study mirrors those findings in a larger, non-human primate species.
During the study, a group of monkeys was injected with the vaccine containing a loop of DNA that enabled them to make IL-15, and were exposed to live SHIV thereafter. The researchers found that the exposure to SHIV did not lead the monkeys to develop any sign of AIDS-like symptoms, as compared to four animals in the control group that received only the DNA vaccine.
The modified vaccine appeared to help suppress viral replication among the IL-15 group. Weiner's team now plans to study the protected macaques to determine the actual mechanism of their protection. The researchers will test the new approach for safety and immunogenicity in humans through the HIV Vaccine Trials Network.