New Delhi: Overcoming a major hurdle in gene therapy, scientists in New Delhi have created particles which can deliver desired DNA to the site in animals' body where it is needed, raising hopes of a more effective delivery system than viruses in treating diseases.

The technology, that involves making nanoparticles and loading them with gene, has been transferred to a US company, American Bioscience Inc.

"We have also patented it," Professor A N Maitra from the Department of Chemistry, Delhi University, whose team developed the technology, told sources in New Delhi.

"Gene therapy aims to treat diseases by correcting defective genes as in cancer or killing invading virus as in deadly HIV. However, the treatment method has remained at experimental stage due to absence of an effective gene delivery mechanism," he said.

Viruses have been used as carriers of genes in experiments. However, their envelope has proteins that illicit strong immunogenic reaction, he said adding in clinical trials there have been cases when patients have died. Of about 500 clinical trials on gene therapy, 70-80 per cent have used viruses as carrier.

The new technology, however, avoids use of viruses and uses small-sized particles made up of calcium phosphate as carriers of gene. The team has investigated the potentiality of this gene delivery system in cancer therapy in animals.