Australian discovery may lead to a hepatitis C vaccine

Researchers in Australia have discovered an antibody that has helped some people develop immunity against hepatitis C, and they hope to use the discovery as the foundation for an HCV vaccine, Agence France-Presse reports. The study of 160 inmates showed that four Australian prisoners had built up a natural immunity to HCV despite repeated exposures to the virus through injection-drug use. Blood tests showed that even when infected with the virus, the prisoners quickly cleared all HCV from their bodies. A separate study of visitors to a Sydney drop-in center for injection-drug users confirmed the researchers' findings. "It seems that the higher the risk behavior, the greater the likelihood the immunity would be present," lead researcher Andrew Lloyd of the University of New South Wales told Agence France-Presse. "I suspect it has something to do with the circumstances of the first exposure. It may be that it was a very low dose that gets into the body and pushes the balance in favor of an immune response." The researchers say a build-up of a naturally occurring antibody that can cripple the virus causes the immunity. Lloyd says his group's findings appear to be similar to those of a study of Kenyan sex workers repeatedly exposed to HIV, but who were able to avoid contracting the disease. Lloyd says his team and other scientists are now working on artificially replicating the naturally occurring antibody for use in a possible vaccine to prevent HCV infection. The full study appears in the August Journal of Infectious Diseases.