Chimp test signals hepatitis vaccine progress
Scientists have created a vaccine for hepatitis C that can induce an immune response in chimpanzees.
The hepatitis C virus is spread through contaminated blood. Infection can lead to permanent scarring of the liver, chronic liver infection and liver failure.
There is currently no vaccine available, and treatment ― costing US$1600–2300 a month for 6 to 12 months ― is beyond the means of most people in the developing world.
Researchers at the US-based National Institutes of Health have shown that a candidate vaccine made up of molecules that resemble parts of the hepatitis C virus can induce an immune response to the virus in animals.
These are attractive as a candidate vaccine because they can induce an immune response, but are not infectious.
Previous attempts to create a hepatitis C vaccine using virus-like particles have resulted in only partial protection from infection.
Immunisation of four chimpanzees with the candidate vaccine resulted in a detectable and sustained immune response for at least six months. When they were inoculated with the hepatitis C virus, they quickly controlled the infection.
In contrast, three out of the four unvaccinated animals became chronically infected with the virus when inoculated.
The researchers also found that the viral levels in the vaccinated animals were five to tenfold lower than those of the control chimpanzees, demonstrating the vaccine's efficacy.
Yet the immune response in the vaccinated animals was still weak. The next stage, according to lead researcher T. Jake Liang, will be to improve the efficacy of the candidate vaccine through genetic modification to induce a stronger immune response against the virus.
Daniel Okenu, a Nigerian scientist at the US-based Morehouse School of Medicine, welcomed the new development and told SciDev.Net that a vaccine would benefit developing countries, as they have limited resources to pay for costly treatment regimes.
He remains sceptical, however, about whether patent regulations will allow this technology to be available to low-income countries.
According to the World Health Organization, most of the estimated 170 million people with hepatitis C worldwide are in developing countries.
Okenu highlighted the need to encourage local production of such vaccines at affordable prices.
The study was published in Proceedings of the National Academy of Sciences last week (7 May).
Link to abstract in PNAS
Ref: Proceeding of the National Academy of Sciences doi 10.1073/pnas.0702162104 (2007)