A virus-like particle vaccine for hepatitis C virus.

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The aim is to evaluate the efficiency of a virus-like particle (VLP) vaccine for hepatitis C virus (HCV). HCV infects about 10,000 people every year in Australia and approximately 8, 000 of these will develop persistent infection. As a result, there are currently 150,000-200,000 HCV carriers in Australia and 500 million worldwide. These individuals represent a source of infection. Although the major route for transmission is blood and blood products, the advent of HCV screening in the blood banks has reduced the risk of infection from this source. However, many intravenous drug users (IVD) share needles and although it is not common, transmission to spouses of carriers is well recognised. In addition, approximately 20% of HCV carriers have no recognised risk factor and it is unclear how these individuals became infected. Transmission of the virus to hospital inpatients and outpatients is also well recognised and as a result, it is clear that a vaccine is urgently required. However, as HCV cannot be cultured in the laboratory, it is impossible to develop a traditional vaccine; furthermore, because a proportion of patients who recover from HCV infection have no specific immunity and thus can be re-infected, the design of a vaccine presents a number of problems. Thus a vaccine which is based on the development of neutralising antibody is unlikely to be effective, in contrast to a vaccine which is designed to generate a cellular immune response. VLPs induce an effective cellular immune response and we plan to make VLPs composed of the L1 protein of bovine papillomavirus (BPV) which is fused to the highly immunogenic HCV core protein or to a string of protein segments (polytope). Laboratory mice will be vaccinated with these VLP and the cellular immune response measured. The vaccine will then be administered to HCV carriers to ensure the safety and the immunological efficacy of the product. This will be assessed serologically and clinically.