Immunogenicity and tolerability of intradermal administration of an HCV E1-based vaccine candidate in healthy volunteers and patients with resolved or ongoing chronic HCV infection.

The tolerability and immunogenicity of intradermal injections of a candidate HCV vaccine, based on the E1 protein of the hepatitis C virus (HCV), was examined in an exploratory study in healthy volunteers, in subjects with a history of resolved HCV infection, and in patients suffering from therapy-resistant chronic HCV. Sub-epidermal injection of three doses of 4 microg of non-adjuvanted E1 vaccine induced much weaker humoral and cellular immune responses in healthy subjects and chronic HCV patients than the intramuscular administration of 20 microg E1 formulated on alum. However, in three subjects who cleared HCV infection, intradermal administration of this low dose of E1 induced rapid and clear anamnestic responses. These data demonstrate that E1-specific immune responses can be induced in resolving HCV infections and that memory (B and T) cells can be restimulated with suboptimal doses of E1 antigen.