OPAL, major discovery in the fight against AIDS

Mar 1 2005

Australian researchers have made a major discovery in the fight against AIDS, with the development of a novel, simple and safe technique for boosting the body’s immune response to deadly viruses like HIV, which is even effective against drug resistant forms of the disease.

Associate Professor Stephen Kent from the University of Melbourne’s Department of Microbiology and Immunology says the findings hold great promise for the treatment of HIV, other chronic viral infections, and drug resistant infections, which are becoming a major problem.

“We have invented a simple new technology to boost the ability of the immune system to fight chronic infections such as AIDS and Hepatitis C. This involves using a patient’s own blood treated with small overlapping proteins of the virus (called peptides),” Associate Professor Kent says.

The research will be published today in the Journal of Virology.

The researchers call the therapy Overlapping Peptide Pulsed Autologous Cells (OPAL). They have been awarded National Health and Medical Research Council (NHMRC) funding of almost $500,000 to refine the technique so that it can be studied in humans.

“The ability to induce and expand the immune response across most or all parts of the virus is highly advantageous. Our results, which consistently demonstrated sharply enhanced immunity in vaccinated animals, suggest that this therapy could also work in humans.”

The researchers initially set out to develop a technique for measuring the effectiveness of a HIV vaccine. They first extracted blood from previously vaccinated animals and then coated the cells with HIV peptide markers (a technique which only takes an hour to complete).

In a normal situation, when HIV or any virus infects a cell, it leaves behind tell-tale markers or peptides on the cell surfaces which tell the immune system that the cell is infected. In this study, the researchers did not infect the animals with HIV, but rather created the illusion to the body that these cells were infected because they had the tell-tale markers (peptides) on their surface.

When they injected this peptide-coated blood back into the vaccinated animals they found that it triggered a huge immune response.

“When we analysed HIV-specific immunity in the weeks following the assays (peptide-coating), a marked enhancement of virus-specific immunity was induced,” Associate Professor Kent says.

“The technique was also effective for boosting the immune response to Hepatitis C peptides and we believe that it could be refined for many different viral infections and cancers. We have also shown it can be used to induce immune responses against drug resistant forms of HIV. The OPAL technique is simpler than current cell-based vaccine techniques which usually require isolation of rare specialised cells from blood.”

Associate Professor Kent led a dedicated team of scientists, Ms Socheata Chea, Dr Jane Dale and Dr Rob De Rose at the University of Melbourne’s Department of Microbiology and Immunology, and collaborated with colleague Dr Ian Ramshaw at the Australian National University’s John Curtin School of Medical Research.

Associate Professor Kent says there is an urgent need to develop simple methods to induce or enhance HIV-specific immunity to prevent or control the disease. “Our research is a major step forward in this regard.”

The researchers will now embark on a series of experiments to refine the technique to make it even more practical and generate even bigger responses. Associate Professor Kent’s group plans to begin human testing of the OPAL therapy in the next one to two years.