SYDNEY, Australia - Australian researchers patented a new way of controlling gene expression that they said is a major improvement on the existing method of using chemical promoters to make an inserted gene work.

Ian Frazer, director of the Center for Immunology and Cancer Research (CICR) in the Medicine Department at Princess Alexandra Hospital in Brisbane, said the technique will allow companies to get around comprehensive patents involving gene expression held by major pharmaceutical companies.

He said biotech companies in all fields have shown an "overwhelming amount of interest" in the work.

The technique worked out by Frazer and scientists at the CICR, and reported in a recent issue of the Journal of Virology, involves taking a closer look at exactly how the target gene is expressed in its host cell.

During research into the papillomavirus Frazer and the late Jian Zhou found each cell has its own slightly different way of expressing genes and skipping over the bits of unwanted and redundant code found in each gene sequence.

Frazer and Zhou learned the key was to look at the transfer RNA (tRNA) that is used as the intermediate step between the gene and the protein. The tRNA for the gene can be collected up and "fingerprinted" to work out the exact way the gene is expressed in its natural surroundings.

Once the exact form of expression is known, the gene in question can be re-engineered to better suit the internal workings of the cell in the type of tissue where it is to be introduced.

Frazer said the new technology allows finer control of genetic expression than the existing techniques involving the use of chemical promoters, so that inserted genes will largely be expressed only in one particular type of cell, such as a stem cell or in one of a number of different types of skin cells.

Among other applications, the technique can be used to switch off a gene - something that promoters cannot do, Frazer said.

The technique potentially has wide applications in genetic engineering, from use in plants, where genetic alteration is routine, to genetic therapy in humans.

UniQuest Pty Ltd., the commercialization arm of the University of Queensland and the affiliated Princess Alexandra Hospital, will sell non-exclusive rights to the technique to companies interested in specific applications.

Frazer said discussions are under way with several interested companies, and that deals may be signed over the next few months.