Nucleic acid molecule that comprise a hepatitis C nonstructural protein including specifically disclosed DNA sequences are disclosed. Pharmaceutical compositions that contain nucleic acid molecules comprising a hepatitis C nonstructural protein including a nucleotide sequence encoding NS3, NS4, or NS5, or a combination thereof, operably linked to regulatory elements functional in human cells are disclosed. Methods of immunizing individuals susceptible to or infected by hepatitis C virus comprising administering such pharaceutical compositions are disclosed.