A hepatitis C virus (HCV) therapeutic vaccine—designed to boost immune control of the virus in people already infected with HCV—has demonstrated that such an approach might work, according to a study presented at the American Association for the Study of Liver Disease (AASLD) Conference in Boston, and reported by aidsmap.

Because HCV mutates so easily, some experts have claimed that it might be impossible to develop a successful preventive vaccine for it. Others, however, have hoped that it might be possible to trigger the body to better control or ward off HCV infection.

To determine whether a vaccine could provoke an effective immune response, Christoph Klade, PhD, from Intercell AG, in Vienna, and his colleagues gave their vaccine, IC41, in two dosing strategies to 50 people living with HCV who had never taken HCV treatment. The participants were not coinfected with HIV. Half received one shallow skin injection of the vaccine every week for 16 weeks. The other half received the shallow skin injection of the vaccine every other week for 16 weeks, combined with a topical immune enhancing agent called imiquimod, which is usually applied to the skin to treat genital warts.

While the first strategy showed no benefit, the second, where the vaccine was combined with imiquimod, did result in a statistically significant drop in HCV levels. The drop in virus was about 50 percent, but those who started off with higher HCV levels experienced a larger drop after vaccination. Most exciting and relevant—these drops in virus were sustained for an additional 20 weeks after the last application of the vaccine and imiquimod combination.

According to aidsmap, the viral load drops were not large enough that the vaccine, as used, would successfully treat HCV, but it does prove that a vaccine can prompt a significant immune response and could possibly work as an adjunct to standard HCV therapy.