Good news for Hep B patients

Scientists have created a powerful new treatment for hepatitis using a revolutionary technique that switches off harmful genes, providing hope for the two billion infected worldwide with the B strain of the virus.

The scientists have found that a few regular injections of the new drug can result in a 90 per cent reduction in the amount of virus circulating in the bloodstream of infected animals.

The replication of the hepatitis B virus is blocked by the phenomenon of RNA interference, which switches off the genes it needs for survival.

Results of a study have shown that RNA interference can work so effectively against invading viruses such as hepatitis that scientists believe the technique can be developed to produce an entirely new class of antiviral drugs.

RNA interference has been described as one of the most exciting developments in medical science and the latest study has shown it is able to stop the spread of hepatitis B virus in infected laboratory mice.

The results of the study, published in the journal Nature Biotechnology, are so encouraging that the scientists are planning to begin the first human trials of RNA interference on hepatitis B patients at the end of next year.

Some two billion people have been infected with the hepatitis B virus and more than 350 million have chronic or lifelong infections that often kill by causing liver cirrhosis and cancer.

Although there are vaccines to protect against infection, the drugs to treat hepatitis B are relatively ineffective as well as being prohibitively expensive for most of the people in the developing world who are chronically infected.

The latest study by David Morrissey and colleagues at the biotechnology company Sirna Therapeutics in Boulder, Colorado, used a form of RNA interference that switches off key genes of the hepatitis virus that it needs to replicate.

Dr Morrissey wrapped short molecules of RNA that were specifically targeted against the hepatitis B virus in a fatty globule that was able to carry or "deliver" the drug into infected cells of the liver.

A few daily injections were followed by a single injection given once a week, which reduced the amount of hepatitis B virus in the bloodstream by 90 per cent, with the effect lasting six weeks.

RNA interference was first described in 1998 and since then it has caused a stir inside the medical community because of its potential to deal with a range of illness, from cancer and viruses to inherited disorders such as Huntington's disease.

Sirna Therapeutics has already begun a trial of RNA interference on patients suffering from age-related macular degeneration, which causes visual impairment in many thousands of people over 50.

About a quarter of people over the age of 65 are affected by the disorder.

Sirna has developed a form of RNA interference designed to switch off or silence a key gene that is thought to stimulate the growth of blood vessels at the back of the eye which leads to macular degeneration.

- INDEPENDENT