In a human trial, an experimental hepatitis C virus vaccine generated immune responses similar to those seen in people who have a rare natural defense against the disease, British and Italian researchers said Wednesday. Forty-one healthy adults participated in the Phase I trial, which suggested the vaccine is safe and is able to stimulate a large T-cell response against HCV that lasts for at least a year.

"The immune responses we've seen are exciting, and we are beginning the next stage of trials. It could be a long road," said lead study author Paul Klenerman of Oxford University.

UK researchers from Oxford and Birmingham universities worked with the Italian biotech firm Okairos to develop a vaccine that stimulates a different part of the immune system from those tried before. The vaccine candidate is designed to generate a T-cell response to internal parts of HCV, which are more constant, rather than an antibody attack on HCV's ever- changing outer coat.

"The outside shell of [HCV] is very variable but the inside of the virus is much more stable," Klenerman said. "That's where the engine of the virus is, where we may be able to successfully target many of the crucial pieces of machinery." A US team is planning a larger trial among at-risk groups to see if the vaccine can help prevent infection. Oxford researchers are starting trials to examine whether it can help people already infected with HCV, as well as working on provoking better immune responses.

"T-cell responses often become weak in those with chronic [HCV] infections," Klenerman said. "It may be that using a vaccine to boost their immunity could become part of any treatment with other drugs." The study, "Novel Adenovirus-Based Vaccines Induce Broad and Sustained T Cell Responses to HCV in Man," was published in Science Translational Medicine (2012;4(115):115ra1).

www.aegis.org