However the impressive variability and adaptation
of HCV to its host make HCV vaccine development a major
challenge (see previous sections). Different epitopes or entire sequences
of HCV proteins are known to induce HCV-specific immune
responses. Indeed, HCV structural proteins are the first targets of
humoral responses while HCV non-structural proteins efficiently
elicit T cell responses. Thus, HCV vaccine candidates have been
developed based on different combinations of HCV antigens as well
as on different delivery systems. In the following section we will
focus on examples for vaccine candidates for prevention of HCV
infection which are in preclinical or early clinical development