Vigorous hepatitis C virus-specific CD4+ and CD8+ T cell responses induced by protein immunization in the presence of Montanide ISA720 plus synthetic oligodeoxynucleotides containing immunostimulatory cytosine-guanine dinucleotide motifs.

Immunization with M-ISA720/CpG/rHCV protein is capable of inducing potent humoral as well as HCV-specific T helper type 1-biased CD4(+) and CD8(+) T cell responses. A DNA boost after a protein prime--a reversal of the conventional approach--may provide an alternative path to the development of an effective HCV vaccine.