Expression system for enhancing solubility and immunogenicity of recombinant proteins. The expression system includes a protein expression vector that contains a chimeric gene encoding a chimeric protein. The chimeric protein contains three polypeptidyl fragments: (a) a first polypeptidyl fragment at the N-terminal end of the chimeric protein that contains a protein transduction domain (PTD) or a fragment thereof having HIV Tat PTD activity; (b) a second polypeptidyl fragment at the C-terminal end of the first polypeptidyl fragment that contains a J-domain or a fragment thereof having heat shock protein 70 (Hsp70)-interacting activity; and (c) a third polypeptidyl fragment at the C-terminal end of the second polypeptidyl fragment that contains a target protein or polypeptide.