A hepatitis C virus (HCV) plasmid vaccine was constructed, based on class II-associated invariant chain peptide (CLIP) substitution which endogenously targets HCV non-structure protein 3 (NS3) CD4(+) stop T helper 1(Th1) epitope (1248AA-1261AA) to major histocompatibility complex (MHC) class II antigen. The in vitro expression results demonstrated that the vaccine was expressed efficiently in COS-7 cell line. The expressed protein could co-localize in endo-membrane system with BALB/c mouse MHC class II molecule I-A(d). The recombinant invariant chain molecule could aggregate with BALB/c mouse I-A(d) molecule and form the theoretical nonomer structure in the COS-7 cell line. The assembled molecules migrate to the cell surface by exocytosis. This has implications for HCV vaccine development.